Physiology of dinosaurs

The physiology of dinosaurs has historically been a controversial subject, particularly their thermoregulation. Recently, many new lines of evidence have been brought to bear on dinosaur physiology generally, including not only metabolic systems and thermoregulation, but on respiratory and cardiovascular systems as well.
During the early years of dinosaur paleontology, it was widely considered that they were sluggish, cumbersome, and sprawling cold-blooded lizards. However, with the discovery of much more complete skeletons in western United States, starting in the 1870s, scientists could make more informed interpretations of dinosaur biology and physiology. Edward Drinker Cope, opponent of Othniel Charles Marsh in the Bone Wars, propounded at least some dinosaurs as active and agile, as seen in the painting of two fighting "Laelaps" produced under his direction by Charles R. Knight.
In parallel, the development of Darwinian evolution, and the discoveries of "Archaeopteryx" and "Compsognathus", led Thomas Henry Huxley to propose that dinosaurs were closely related to birds. Despite these considerations, the image of dinosaurs as large reptiles had already taken root, and most aspects of their paleobiology were interpreted as being typically reptilian for the first half of the twentieth century. Beginning in the 1960s and with the advent of the Dinosaur Renaissance, views of dinosaurs and their physiology have changed dramatically, including the discovery of feathered dinosaurs in Early Cretaceous age deposits in China, indicating that birds evolved from highly agile maniraptoran dinosaurs.
History of study.
Early interpretations of dinosaurs: 1820s to early 1900s.
The study of dinosaurs began in the 1820s in England. Pioneers in the field, such as William Buckland, Gideon Mantell, and Richard Owen, interpreted the first, very fragmentary remains as belonging to large quadrupedal beasts. Their early work can be seen today in the Crystal Palace Dinosaurs, constructed in the 1850s, which present known dinosaurs as elephantine lizard-like reptiles. Despite these reptilian appearances, Owen speculated that dinosaur heart and respiratory systems were more similar to that of a mammal than a reptile.
Changing views and the dinosaur renaissance.
In the late 1960s, similar ideas reappeared, beginning with John Ostrom's work on "Deinonychus" and bird evolution. His student, Bob Bakker, popularized the changing thought in a series of papers beginning with "The superiority of dinosaurs" in 1968. In these publications, he argued strenuously that dinosaurs were warm-blooded and active animals, capable of sustained periods of high activity. In most of his writings Bakker framed his arguments as new evidence leading to a revival of ideas popular in the late 19th century, frequently referring to an ongoing "dinosaur renaissance". He used a variety of anatomical and statistical arguments to defend his case, the methodology of which was fiercely debated among scientists.
These debates sparked interest in new methods for ascertaining the palaeobiology of extinct animals, such as bone histology, which have been successfully applied to determining the growth-rates of many dinosaurs.
Today, it is generally thought that many or perhaps all dinosaurs had higher metabolic rates than living reptiles, but also that the situation is more complex and varied than Bakker originally proposed. For example, while smaller dinosaurs may have been true endotherms, the larger forms could have been inertial homeotherms, or that many dinosaurs could have had intermediate metabolic rates.
Feeding and digestion.
The earliest dinosaurs were almost certainly predators, and shared several predatory features with their nearest non-dinosaur relatives like "Lagosuchus", including: relatively large, curved, blade-like teeth in large, wide-opening jaws that closed like scissors; relatively small abdomens, as carnivores do not require large digestive systems. Later dinosaurs regarded as predators sometimes grew much larger, but retained the same set of features. Instead of chewing their food, these predators swallowed it whole.
The feeding habits of ornithomimosaurs and oviraptorosaurs are a mystery: although they evolved from a predatory theropod lineage, they have small jaws and lack the blade-like teeth of typical predators, but there is no evidence of their diet or how they ate and digested it.
Features of other groups of dinosaurs indicate they were herbivores. These features include:
Sauropods, which were herbivores, did not chew their food, as their teeth and jaws appear suitable only for stripping leaves off plants. Ornithischians, also herbivores, show a variety of approaches. The armored ankylosaurs and stegosaurs had small heads and weak jaws and teeth, and are thought to have fed in much the same way as sauropods. The pachycephalosaurs had small heads and weak jaws and teeth, but their lack of large digestive systems suggests a different diet, possibly fruits, seeds, or young shoots, which would have been more nutritious to them than leaves.
On the other hand, ornithopods such as "Hypsilophodon", "Iguanodon" and various hadrosaurs had horny beaks for snipping off vegetation and jaws and teeth that were well-adapted for chewing. The horned ceratopsians had similar mechanisms.
It has often been suggested that at least some dinosaurs used swallowed stones, known as gastroliths, to aid digestion by grinding their food in muscular gizzards, and that this was a feature they shared with birds. In 2007 Oliver Wings reviewed references to gastroliths in scientific literature and found considerable confusion, starting with the lack of an agreed and objective definition of "gastrolith". He found that swallowed hard stones or grit can assist digestion in birds that mainly feed on grain but may not be essential—and that birds that eat insects in summer and grain in winter usually get rid of the stones and grit in summer. Gastroliths have often been described as important for sauropod dinosaurs, whose diet of vegetation required very thorough digestion, but Wings concluded that this idea was incorrect: gastroliths are found with only a small percentage of sauropod fossils; where they have been found, the amounts are too small and in many cases the stones are too soft to have been effective in grinding food; most of these gastroliths are highly polished, but gastroliths used by modern animals to grind food are roughened by wear and corroded by stomach acids; hence the sauropod gastroliths were probably swallowed accidentally. On the other hand, he concluded that gastroliths found with fossils of advanced theropod dinosaurs such as "Sinornithomimus" and "Caudipteryx" resemble those of birds, and that the use of gastroliths for grinding food may have appeared early in the group of dinosaurs from which these dinosaurs and birds both evolved.
Reproductive biology.
When laying eggs, female birds grow a special type of bone in their limbs between the hard outer bone and the marrow. This medullary bone, which is rich in calcium, is used to make eggshells, and the birds that produced it absorb it when they have finished laying eggs. Medullary bone has been found in fossils of the theropods "Tyrannosaurus" and "Allosaurus" and of the ornithopod "Tenontosaurus".
Because the line of dinosaurs that includes "Allosaurus" and "Tyrannosaurus" diverged from the line that led to "Tenontosaurus" very early in the evolution of dinosaurs, the presence of medullary bone in both groups suggests that dinosaurs in general produced medullary tissue. On the other hand, crocodilians, which are dinosaurs' second closest extant relatives after birds, do not produce medullary bone. This tissue may have first appeared in ornithodires, the Triassic archosaur group from which dinosaurs are thought to have evolved.
Medullary bone has been found in specimens of sub-adult size, which suggests that dinosaurs reached sexual maturity before they were full-grown. Sexual maturity at sub-adult size is also found in reptiles and in medium- to large-sized mammals, but birds and small mammals reach sexual maturity only after they are full-grown—which happens within their first year. Early sexual maturity is also associated with specific features of animals' life cycles: the young are born relatively well-developed rather than helpless; and the death-rate among adults is high.
Respiratory system.
Air sacs.
From about 1870 onwards scientists have generally agreed that the post-cranial skeletons of many dinosaurs contained many air-filled cavities (postcranial skeletal pneumaticity, especially in the vertebrae. Pneumatization of the skull (such as paranasal sinuses) is found in both synapsids and archosaurs, but postcranial pneumatization is found only in birds, non-avian saurischian dinosaurs, and pterosaurs.
For a long time these cavities were regarded simply as weight-saving devices, but Bakker proposed that they were connected to air sacs like those that make birds' respiratory systems the most efficient of all animals'.
John Ruben "et al." (1997, 1999, 2003, 2004) disputed this and suggested that dinosaurs had a "tidal" respiratory system (in and out) powered by a crocodile-like hepatic piston mechanism – muscles attached mainly to the pubis pull the liver backwards, which makes the lungs expand to inhale; when these muscles relax, the lungs return to their previous size and shape, and the animal exhales. They also presented this as a reason for doubting that birds descended from dinosaurs.
Critics have claimed that, without avian air sacs, modest improvements in a few aspects of a modern reptile's circulatory and respiratory systems would enable the reptile to achieve 50% to 70% of the oxygen flow of a mammal of similar size, and that lack of avian air sacs would not prevent the development of endothermy. Very few formal rebuttals have been published in scientific journals of Ruben et al.'s claim that dinosaurs could not have had avian-style air sacs; but one points out that the "Sinosauropteryx" fossil on which they based much of their argument was severely flattened and therefore it was impossible to tell whether the liver was the right shape to act as part of a hepatic piston mechanism. Some recent papers simply note without further comment that Ruben et al. argued against the presence of air sacs in dinosaurs.
Researchers have presented evidence and arguments for air sacs in sauropods, "prosauropods", coelurosaurs, ceratosaurs, and the theropods "Aerosteon" and "Coelophysis".
In advanced sauropods ("neosauropods") the vertebrae of the lower back and hip regions show signs of air sacs. In early sauropods only the cervical (neck) vertebrae show these features. If the developmental sequence found in bird embryos is a guide, air sacs actually evolved before the channels in the skeleton that accommodate them in later forms.
Evidence of air sacs has also been found in theropods. Studies indicate that fossils of coelurosaurs, ceratosaurs, and the theropods "Coelophysis" and "Aerosteon" exhibit evidence of air sacs. "Coelophysis", from the late Triassic, is one of the earliest dinosaurs whose fossils show evidence of channels for air sacs. "Aerosteon", a Late Cretaceous allosaur, had the most bird-like air sacs found so far.
Early sauropodomorphs, including the group traditionally called "prosauropods", may also have had air sacs. Although possible pneumatic indentations have been found in "Plateosaurus" and "Thecodontosaurus", the indentations are very small. One study in 2007 concluded that prosauropods likely had abdominal and cervical air sacs, based on the evidence for them in sister taxa (theropods and sauropods). The study concluded that it was impossible to determine whether prosauropods had a bird-like flow-through lung, but that the air sacs were almost certainly present. A further indication for the presence of air sacs and their use in lung ventilation comes from a reconstruction of the air exchange volume (the volume of air exchanged with each breath) of "Plateosaurus", which when expressed as a ratio of air volume per body weight at 29 ml/kg is similar to values of geese and other birds, and much higher than typical mammalian values.
So far no evidence of air sacs has been found in ornithischian dinosaurs. But this does not imply that ornithischians could not have had metabolic rates comparable to those of mammals, since mammals also do not have air sacs.
Three explanations have been suggested for the development of air sacs in dinosaurs:
Calculations of the volumes of various parts of the sauropod "Apatosaurus" respiratory system support the evidence of bird-like air sacs in sauropods:
On this basis, "Apatosaurus" could not have had a reptilian respiratory system, as its tidal volume would have been less than its dead-space volume, so that stale air was not expelled but was sucked back into the lungs. Likewise, a mammalian system would only provide to the lungs about 225 − 184 = 41 liters of fresh, oxygenated air on each breath. "Apatosaurus" must therefore have had either a system unknown in the modern world or one like birds', with multiple air sacs and a flow-through lung. Furthermore, an avian system would only need a lung volume of about 600 liters while a mammalian one would have required about 2,950 liters, which would exceed the estimated 1,700 liters of space available in a 30-ton "Apatosaurus"′ chest.
Dinosaur respiratory systems with bird-like air sacs may have been capable of sustaining higher activity levels than mammals of similar size and build can sustain. In addition to providing a very efficient supply of oxygen, the rapid airflow would have been an effective cooling mechanism, which is essential for animals that are active but too large to get rid of all the excess heat through their skins.
The palaeontologist Peter Ward has argued that the evolution of the air sac system, which first appears in the very earliest dinosaurs, may have been in response to the very low (11%) atmospheric oxygen of the Carnian and Norian ages of the Triassic Period.
Uncinate processes on the ribs.
Birds have spurs called "uncinate processes" on the rear edges of their ribs, and these give the chest muscles more leverage when pumping the chest to improve oxygen supply. The size of the uncinate processes is related to the bird's lifestyle and oxygen requirements: they are shortest in walking birds and longest in diving birds, which need to replenish their oxygen reserves quickly when they surface. Non-avian maniraptoran dinosaurs also had these uncinate processes, and they were proportionately as long as in modern diving birds, which indicates that maniraptorans needed a high-capacity oxygen supply.
Plates that may have functioned the same way as uncinate processes have been observed in fossils of the ornithischian dinosaur "Thescelosaurus", and have been interpreted as evidence of high oxygen consumption and therefore high metabolic rate.
Nasal turbinates.
Nasal turbinates are convoluted structures of thin bone in the nasal cavity. In most mammals and birds these are present and lined with mucous membranes that perform two functions. They improve the sense of smell by increasing the area available to absorb airborne chemicals, and they warm and moisten inhaled air, and extract heat and moisture from exhaled air to prevent desiccation of the lungs.
John Ruben and others have argued that no evidence of nasal turbinates has been found in dinosaurs. All the dinosaurs they examined had nasal passages that were too narrow and short to accommodate nasal turbinates, so dinosaurs could not have sustained the breathing rate required for a mammal-like or bird-like metabolic rate while at rest, because their lungs would have dried out. However, objections have been raised against this argument. Nasal turbinates are absent or very small in some birds (e.g. ratites, Procellariiformes and Falconiformes) and mammals (e.g. whales, anteaters, bats, elephants, and most primates), although these animals are fully endothermic and in some cases very active. Other studies conclude that nasal turbinates are fragile and seldom found in fossils. In particular none have been found in fossil birds.
In 2014 Jason Bourke and others in "Anatomical Record" reported finding nasal turbinates in pachycephalosaurs.
Cardiovascular system.
In principle one would expect dinosaurs to have had two-part circulations driven by four-chambered hearts, since many would have needed high blood pressure to deliver blood to their heads, which were high off the ground, but vertebrate lungs can only tolerate fairly low blood pressure. In 2000, a skeleton of "Thescelosaurus", now on display at the North Carolina Museum of Natural Sciences, was described as including the remnants of a four-chambered heart and an aorta. The authors interpreted the structure of the heart as indicating an elevated metabolic rate for "Thescelosaurus", not reptilian cold-bloodedness. Their conclusions have been disputed; other researchers published a paper where they assert that the heart is really a concretion of entirely mineral "cement". As they note: the anatomy given for the object is incorrect, for example the alleged "aorta" is narrowest where it meets the "heart" and lacks arteries branching from it; the "heart" partially engulfs one of the ribs and has an internal structure of concentric layers in some places; and another concretion is preserved behind the right leg. The original authors defended their position; they agreed that the chest did contain a type of concretion, but one that had formed around and partially preserved the more muscular portions of the heart and aorta.
Regardless of the object's identity, it may have little relevance to dinosaurs' internal anatomy and metabolic rate. Both modern crocodilians and birds, the closest living relatives of dinosaurs, have four-chambered hearts, although modified in crocodilians, and so dinosaurs probably had them as well. However such hearts are not necessarily tied to metabolic rate.
Growth and lifecycle.
No dinosaur egg has been found that is larger than a basketball and embryos of large dinosaurs have been found in relatively small eggs, e.g. Maiasaura. Like mammals, dinosaurs stopped growing when they reached the typical adult size of their species, while mature reptiles continued to grow slowly if they had enough food. Dinosaurs of all sizes grew faster than similarly sized modern reptiles; but the results of comparisons with similarly sized "warm-blooded" modern animals depend on their sizes:
"Tyrannosaurus rex" showed a "teenage growth spurt":
A 2008 study of one skeleton of the hadrosaur "Hypacrosaurus" concluded that this dinosaur grew even faster, reaching its full size at the age of about 15; the main evidence was the number and spacing of growth rings in its bones. The authors found this consistent with a life-cycle theory that prey species should grow faster than their predators if they lose a lot of juveniles to predators and the local environment provides enough resources for rapid growth.
It appears that individual dinosaurs were rather short-lived, e.g. the oldest (at death) "Tyrannosaurus" found so far was 28 and the oldest sauropod was 38. Predation was probably responsible for the high death rate of very young dinosaurs and sexual competition for the high death rate of sexually mature dinosaurs.
Metabolism.
Scientific opinion about the life-style, metabolism and temperature regulation of dinosaurs has varied over time since the discovery of dinosaurs in the mid-19th century. The activity of metabolic enzymes varies with temperature, so temperature control is vital for any organism, whether endothermic or ectothermic. Organisms can be categorized as poikilotherms (poikilo – changing), which are tolerant of internal temperature fluctuations, and homeotherms (homeo – same), which must maintain a constant core temperature. Animals can be further categorized as endotherms, which regulate their temperature internally, and ectotherms, which regulate temperature by the use of external heat sources.
What the debate is about.
"Warm-bloodedness" is a complex and rather ambiguous term, because it includes some or all of:
Large dinosaurs may also have maintained their temperatures by inertial homeothermy, also known as "bulk homeothermy" or "mass homeothermy". In other words, the thermal capacity of such large animals was so high that it would take two days or more for their temperatures to change significantly, and this would have smoothed out variations caused by daily temperature cycles. This smoothing effect has been observed in large turtles and crocodilians, but "Plateosaurus", which weighed about , may have been the smallest dinosaur in which it would have been effective. Inertial homeothermy would not have been possible for small species nor for the young of larger species. Vegetation fermenting in the guts of large herbivores can also produce considerable heat, but this method of maintaining a high and stable temperature would not have been possible for carnivores or for small herbivores or the young of larger herbivores.
Since the internal mechanisms of extinct creatures are unknowable, most discussion focuses on homeothermy and tachymetabolism.
Assessment of metabolic rates is complicated by the distinction between the rates while resting and while active. In all modern reptiles and most mammals and birds the maximum rates during all-out activity are 10 to 20 times higher than minimum rates while at rest. However, in a few mammals these rates differ by a factor of 70. Theoretically it would be possible for a land vertebrate to have a reptilian metabolic rate at rest and a bird-like rate while working flat out. However, an animal with such a low resting rate would be unable to grow quickly. The huge herbivorous sauropods may have been on the move so constantly in search of food that their energy expenditure would have been much the same irrespective of whether their resting metabolic rates were high or low.
Metabolic options.
The main possibilities are that:
Dinosaurs were around for about 150 million years, so it is very likely that different groups evolved different metabolisms and thermoregulatory regimes, and that some developed different physiologies from the first dinosaurs.
If all or some dinosaurs had intermediate metabolisms, they may have had the following features:
Robert Reid has suggested that such animals could be regarded as "failed endotherms". He envisaged both dinosaurs and the Triassic ancestors of mammals passing through a stage with these features. Mammals were forced to become smaller as archosaurs came to dominate ecological niches for medium to large animals. Their decreasing size made them more vulnerable to heat loss because it increased their ratios of surface area to mass, and thus forced them to increase internal heat generation and thus become full endotherms. On the other hand, dinosaurs became medium to very large animals and thus were able to retain the "intermediate" type of metabolism.
Bone structure.
Armand de Ricqlès discovered Haversian canals in dinosaur bones, and argued that there was evidence of endothermy in dinosaurs. These canals are common in "warm-blooded" animals and are associated with fast growth and an active life style because they help to recycle bone to facilitate rapid growth and repair damage caused by stress or injuries. Dense secondary Haversian bone, which is formed during remodeling, is found in many living endotherms as well as dinosaurs, pterosaurs and therapsids. Secondary Haversian canals are correlated with size and age, mechanical stress and nutrient turnover. The presence of secondary Haversian canals suggests comparable bone growth and lifespans in mammals and dinosaurs. Bakker argued that the presence of fibrolamellar bone (produced quickly and having a fibrous, woven appearance) in dinosaur fossils was evidence of endothermy.
However, as a result of other, mainly later research, bone structure is not considered a reliable indicator of metabolism in dinosaurs, mammals or reptiles:
Nevertheless, de Ricqlès persevered with studies of the bone structure of dinosaurs and archosaurs. In mid-2008 he co-authored a paper that examined bone samples from a wide range of archosaurs, including early dinosaurs, and concluded that:
An osteohistological analysis of vascular density and density, shape and area of osteocytes concluded non-avian dinosaurs and the majority of archosauriforms (except "Proterosuchus", crocodilians and phytosaurs) retained heat and had resting metabolic rates similar to those of extant mammals and birds.
Metabolic rate, blood pressure and flow.
Endotherms rely highly on aerobic metabolism and have high rates of oxygen consumption during activity and rest. The oxygen required by the tissues is carried by the blood, and consequently blood flow rates and blood pressures at the heart of warm-blooded endotherms are considerably higher than those of cold-blooded ectotherms. It is possible to measure the minimum blood pressures of dinosaurs by estimating the vertical distance between the heart and the top of the head, because this column of blood must have a pressure at the bottom equal to the hydrostatic pressure derived from the density of blood and gravity. Added to this pressure is that required to move the blood through the circulatory system. It was pointed out in 1976 that, because of their height, many dinosaurs had minimum blood pressures within the endothermic range, and that they must have had four-chambered hearts to separate the high pressure circuit to the body from the low pressure circuit to the lungs. It was not clear whether these dinosaurs had high blood pressure simply to support the blood column or to support the high blood flow rates required by endothermy or both.
However, recent analysis of the tiny holes in fossil leg bones of dinosaurs provides a gauge for blood flow rate and hence metabolic rate. The holes are called nutrient foramina, and the nutrient artery is the major blood vessel passing through to the interior of the bone, where it branches into tiny vessels of the Haversian canal system. This system is responsible for replacing old bone with new bone, thereby repairing microbreaks that occur naturally during locomotion. Without this repair, microbreaks would build up, leading to stress fractures and ultimately catastrophic bone failure. The size of the nutrient foramen provides an index of blood flow through it, according to the Hagen-Poiseuille equation. The size is also related to the body size of animal, of course, so this effect is removed by analysis of allometry. Blood flow index of the nutrient foramen of the femurs in living mammals increases in direct proportion to the animals' maximum metabolic rates, as measured during maximum sustained locomotion. Mammalian blood flow index is about 10 times greater than in ectothermic reptiles. Ten species of fossil dinosaurs from five taxonomic groups reveal indices even higher than in mammals, when body size is accounted for, indicating that they were highly active, aerobic animals. Thus high blood flow rate, high blood pressure, a four-chambered heart and sustained aerobic metabolism are all consistent with endothermy.
Growth rates.
Dinosaurs grew from small eggs to several tons in weight relatively quickly. A natural interpretation of this is that dinosaurs converted food into body weight very quickly, which requires a fairly fast metabolism both to forage actively and to assimilate the food quickly. Developing bone found in juveniles is distinctly porous, which has been linked to vascularization and bone deposition rate, all suggesting growth rates close to those observed in modern birds.
But a preliminary study of the relationship between adult size, growth rate, and body temperature concluded that larger dinosaurs had higher body temperatures than smaller ones had; "Apatosaurus", the largest dinosaur in the sample, was estimated to have a body temperature exceeding , whereas smaller dinosaurs were estimated to have body temperatures around  – for comparison, normal human body temperature is about . Based on these estimations, the study concluded that large dinosaurs were inertial homeotherms (their temperatures were stabilized by their sheer bulk) and that dinosaurs were ectothermic (in colloquial terms, "cold-blooded", because they did not generate as much heat as mammals when not moving or digesting food). These results are consistent with the relationship between dinosaurs' sizes and growth rates (described above). Studies of the sauropodomorph "Massospondylus" and early theropod "Syntarsus" ("Megapnosaurus") reveal growth rates of 3 kg/year and 17 kg/year, respectively, much slower than those estimated of "Maiasaura" and observed in modern birds.
Oxygen isotope ratios in bone.
The ratio of the isotopes 16O and 18O in bone depends on the temperature the bone formed at: the higher the temperature, the more 16O. Barrick and Showers (1999) analyzed the isotope ratios in two theropods that lived in temperate regions with seasonal variation in temperature, "Tyrannosaurus" (USA) and "Giganotosaurus" (Argentina):
Barrick and Showers concluded that both dinosaurs were endothermic but at lower metabolic levels than modern mammals, and that inertial homeothermy was an important part of their temperature regulation as adults. Their similar analysis of some Late Cretaceous ornithischians in 1996 concluded that these animals showed a similar pattern.
However this view has been challenged. The evidence indicates homeothermy, but by itself cannot prove endothermy. Secondly, the production of bone may not have been continuous in areas near the extremities of limbs – in allosaur skeketons lines of arrested growth ("LAGs"; rather like growth rings) are sparse or absent in large limb bones but common in the fingers and toes. While there is no absolute proof that LAGs are temperature-related, they could mark times when the extremities were so cool that the bones ceased to grow. If so, the data about oxygen isotope ratios would be incomplete, especially for times when the extremities were coolest. Oxygen isotope ratios may be an unreliable method of estimating temperatures if it cannot be shown that bone growth was equally continuous in all parts of the animal.
Predator–prey ratios.
Bakker argued that:
This argument was criticized on several grounds and is no longer taken seriously (the following list of criticisms is far from exhaustive):
Posture and gait.
Dinosaurs' limbs were erect and held under their bodies, rather than sprawling out to the sides like those of lizards and newts. The evidence for this is the angles of the joint surfaces and the locations of muscle and tendon attachments on the bones. Attempts to represent dinosaurs with sprawling limbs result in creatures with dislocated hips, knees, shoulders and elbows.
Carrier's constraint states that air-breathing vertebrates with two lungs that flex their bodies sideways during locomotion find it difficult to move and breathe at the same time. This severely limits stamina, and forces them to spend more time resting than moving.
Sprawling limbs require sideways flexing during locomotion (except for tortoises and turtles, which are very slow and whose armor keeps their bodies fairly rigid). However, despite Carrier's constraint, sprawling limbs are efficient for creatures that spend most of their time resting on their bellies and only move for a few seconds at a time—because this arrangement minimizes the energy costs of getting up and lying down.
Erect limbs increase the costs of getting up and lying down, but avoid Carrier's constraint. This indicates that dinosaurs were active animals because natural selection would have favored the retention of sprawling limbs if dinosaurs had been sluggish and spent most of their waking time resting. An active lifestyle requires a metabolism that quickly regenerates energy supplies and breaks down waste products which cause fatigue, i.e., it requires a fairly fast metabolism and a considerable degree of homeothermy.
Additionally, an erect posture demands precise balance, the result of a rapidly functioning neuromuscular system. This suggests endothermic metabolism, because an ectothermic animal would be unable to walk or run, and thus to evade predators, when its core temperature was lowered. Other evidence for endothermy includes limb length (many dinosaurs possessed comparatively long limbs) and bipedalism, both found today only in endotherms. Many bipedal dinosaurs possessed gracile leg bones with a short thigh relative to calf length. This is generally an adaptation to frequent sustained running, characteristic of endotherms which, unlike ectotherms, are capable of producing sufficient energy to stave off the onset of anaerobic metabolism in the muscle.
Bakker and Ostrom both pointed out that all dinosaurs had erect hindlimbs and that all quadrupedal dinosaurs had erect forelimbs; and that among living animals only the endothermic ("warm-blooded") mammals and birds have erect limbs (Ostrom acknowledged that crocodilians' occasional "high walk" was a partial exception). Bakker claimed this was clear evidence of endothermy in dinosaurs, while Ostrom regarded it as persuasive but not conclusive.
A 2009 study supported the hypothesis that endothermy was widespread in at least larger non-avian dinosaurs, and that It was plausibly ancestral for all dinosauriforms, based on the biomechanics of running, though it has also been suggested that endothermy appeared much earlier in archosauromorph evolution, perhaps even preceding the origin of Archosauriformes.
There is now no doubt that many theropod dinosaur species had feathers, including "Shuvuuia", "Sinosauropteryx" and "Dilong" (an early tyrannosaur). These have been interpreted as insulation and therefore evidence of warm-bloodedness.
But direct, unambiguous impressions of feathers have only been found in coelurosaurs (which include the birds and tyrannosaurs, among others), so at present feathers give us no information about the metabolisms of the other major dinosaur groups, e.g. coelophysids, ceratosaurs, carnosaurs, or sauropods. Filamentous integument was also present in at least some ornithischians, such as "Tianyulong", "Kulindadromeus" and "Psittacosaurus", not only indicating endothermy in this group, but also that feathers were already present in the first ornithodiran (the last common ancestor of dinosaurs and pterosaurs). Their absence in certain groups like Ankylosauria could be the result of suppression of feather genes.
The fossilised skin of "Carnotaurus" (an abelisaurid and therefore not a coelurosaur) shows an unfeathered, reptile-like skin with rows of bumps, but the conclusion that "Carnotaurus" was necessarily featherless has been criticized as the impressions do not cover the whole body, being found only in the lateral region but not the dorsum. An adult "Carnotaurus" weighed about 2 tonnes, and mammals of this size and larger have either very short, sparse hair or naked skins, so perhaps the skin of "Carnotaurus" tells us nothing about whether smaller non-coelurosaurian theropods had feathers. The tyrannosauroid "Yutyrannus" is known to have possessed feathers and weighed 1.1 tonne.
Skin-impressions of "Pelorosaurus" and other sauropods (dinosaurs with elephantine bodies and long necks) reveal large hexagonal scales, and some sauropods, such as "Saltasaurus", had bony plates in their skin. The skin of ceratopsians consisted of large polygonal scales, sometimes with scattered circular plates. "Mummified" remains and skin impressions of hadrosaurids reveal pebbly scales. It is unlikely that the ankylosaurids, such as "Euoplocephalus", had insulation, as most of their surface area was covered in bony knobs and plates. Likewise there is no evidence of insulation in the stegosaurs. Thus insulation, and the elevated metabolic rate behind evolving them, may have been limited to the theropods, or even just a subset of theropods. Lack of feathers or other sort of insulation does not indicate ectothermy or low metabolisms, as observed in the relative hairlessness of mammalian megafauna, pigs, human children and the hairless bat being compatible with endothermy.
Polar dinosaurs.
Dinosaur fossils have been found in regions that were close to the poles at the relevant times, notably in southeastern Australia, Antarctica and the North Slope of Alaska. There is no evidence of major changes in the angle of the Earth's axis, so polar dinosaurs and the rest of these ecosystems would have had to cope with the same extreme variation of day length through the year that occurs at similar latitudes today (up to a full day with no darkness in summer, and a full day with no sunlight in winter).
Studies of fossilized vegetation suggest that the Alaska North Slope had a maximum temperature of and a minimum temperature of to in the last 35 million years of the Cretaceous (slightly cooler than Portland, Oregon but slightly warmer than Calgary, Alberta). Even so, the Alaska North Slope has no fossils of large cold-blooded animals such as lizards and crocodilians, which were common at the same time in Alberta, Montana, and Wyoming. This suggests that at least some non-avian dinosaurs were warm-blooded. It has been proposed that North American polar dinosaurs may have migrated to warmer regions as winter approached, which would allow them to inhabit Alaska during the summers even if they were cold-blooded. But a round trip between there and Montana would probably have used more energy than a cold-blooded land vertebrate produces in a year; in other words the Alaskan dinosaurs would have to be warm-blooded, irrespective of whether they migrated or stayed for the winter. A 2008 paper on dinosaur migration by Phil R. Bell and Eric Snively proposed that most polar dinosaurs, including theropods, sauropods, ankylosaurians, and hypsilophodonts, probably overwintered, although hadrosaurids like "Edmontosaurus" were probably capable of annual round trips.
It is more difficult to determine the climate of southeastern Australia when the dinosaur fossil beds were laid down , towards the end of the Early Cretaceous: these deposits contain evidence of permafrost, ice wedges, and hummocky ground formed by the movement of subterranean ice, which suggests mean annual temperatures ranged between and ; oxygen isotope studies of these deposits give a mean annual temperature of to . However the diversity of fossil vegetation and the large size of some of fossil trees exceed what is found in such cold environments today, and no-one has explained how such vegetation could have survived in the cold temperatures suggested by the physical indicators – for comparison Fairbanks, Alaska presently has a mean annual temperature of . An annual migration from and to southeastern Australia would have been very difficult for fairly small dinosaurs in such as "Leaellynasaura", a herbivore about to long, because seaways to the north blocked the passage to warmer latitudes. Bone samples from "Leaellynasaura" and "Timimus", an ornithomimid about long and high at the hip, suggested these two dinosaurs had different ways of surviving the cold, dark winters: the "Timimus" sample had lines of arrested growth (LAGs for short; similar to growth rings), and it may have hibernated; but the "Leaellynasaura" sample showed no signs of LAGs, so it may have remained active throughout the winter. A 2011 study focusing on hypsilophodont and theropod bones also concluded that these dinosaurs did not hibernate through the winter, but stayed active.
Evidence for behavioral thermoregulation.
Some dinosaurs, e.g. "Spinosaurus" and "Ouranosaurus", had on their backs "sails" supported by spines growing up from the vertebrae. (This was also true, incidentally, for the synapsid "Dimetrodon".) Such dinosaurs could have used these sails to:
But these were a very small minority of known dinosaur species.
One common interpretation of the plates on stegosaurs' backs is as heat exchangers for thermoregulation, as the plates are filled with blood vessels, which, theoretically, could absorb and dissipate heat.
 This might have worked for a stegosaur with large plates, such as "Stegosaurus", but other stegosaurs, such as "Wuerhosaurus", "Tuojiangosaurus" and "Kentrosaurus" possessed much smaller plates with a surface area of doubtful value for thermo-regulation. However, the idea of stegosaurian plates as heat exchangers has recently been questioned.
Other evidence.
Endothermy demands frequent respiration, which can result in water loss. In living birds and mammals, water loss is limited by pulling moisture out of exhaled air with mucous-covered respiratory turbinates, tissue-covered bony sheets in the nasal cavity. Several dinosaurs have olfactory turbinates, used for smell, but none have yet been identified with respiratory turbinates.
Because endothermy allows refined neuromuscular control, and because brain matter requires large amounts of energy to sustain, some speculate that increased brain size indicates increased activity and, thus, endothermy. The encephalization quotient (EQ) of dinosaurs, a measure of brain size calculated using brain endocasts, varies on a spectrum from bird-like to reptile-like. Using EQ alone, coelurosaurs appear to have been as active as living mammals, while theropods and ornithopods fall somewhere between mammals and reptiles, and other dinosaurs resemble reptiles.
A study published by Roger Seymour in 2013 added more support to the idea that dinosaurs were endothermic. After studying saltwater crocodiles, Seymour found that even if their large sizes could provide stable and high body temperatures, during activity the crocodile's ectothermic metabolism provided less aerobic abilities and generate only 14% of the total muscle power of a similar sized endothermic mammal before full fatigue. Seymour reasoned that dinosaurs would have needed to be endothermic since they would have needed better aerobic abilities and higher power generation to compete with and dominate over mammals as active land animals throughout the Mesozoic era.
The crocodilian puzzle and early archosaur metabolism.
It appears that the earliest dinosaurs had the features that form the basis for arguments for warm-blooded dinosaurs—especially erect limbs. This raises the question "How did dinosaurs become warm-blooded?" The most obvious possible answers are:
Crocodilians present some puzzles if one regards dinosaurs as active animals with fairly constant body temperatures. Crocodilians evolved shortly before dinosaurs and, second to birds, are dinosaurs' closest living relatives – but modern crocodilians are cold-blooded. This raises some questions:
Modern crocodilians are cold-blooded but can move with their limbs erect, and have several features normally associated with warm-bloodedness because they improve the animal's oxygen supply:
So why did natural selection favor these features, which are important for active warm-blooded creatures but of little apparent use to cold-blooded aquatic ambush predators that spend most of their time floating in water or lying on river banks?
It was suggested in the late 1980s that crocodilians were originally active, warm-blooded predators and that their archosaur ancestors were warm-blooded. More recently, developmental studies indicate that crocodilian embryos develop fully four-chambered hearts first—then develop the modifications that make their hearts function as three-chambered under water. Using the principle that ontogeny recapitulates phylogeny, the researchers concluded that the original crocodilians had fully 4-chambered hearts and were therefore warm-blooded and that later crocodilians developed the bypass as they reverted to being cold-blooded aquatic ambush predators.
More recent research on archosaur bone structures and their implications for growth rates also suggests that early archosaurs had fairly high metabolic rates and that the Triassic ancestors of crocodilians dropped back to more typically "reptilian" metabolic rates.
If this view is correct, the development of warm-bloodedness in archosaurs (reaching its peak in dinosaurs) and in mammals would have taken more similar amounts of time. It would also be consistent with the fossil evidence:


Pseudoceros goslineri

Pseudoceros goslineri, the Gosliner flatworm, is a marine flatworm species that belongs to the family Pseudocerotidae.
Distribution.
It is found in the tropical Indo-Pacific, from the eastern coast of Africa to the Micronesia, including the Red Sea.
Habitat.
External slope or top on coral reef.
Size.
Up to .
Physical characteristics.
"External anatomy: Flatworm with irregular and variable color pattern characterized mainly by a cream background mottled with orange, and pink and purple-red dots concentrated medially forming an elongated blotch. The margin consists of purple and pink irregular spots and dots that are more concentrated on the tentacles making the tips a little darker. The ventral side is light violet. Pseudotentacles formed by simple folds of the anterior margin with few marginal eyes. Cerebral cluster made of about 30 eyespots. Presence of a broad folded pharynx.
Internal anatomy: The male reproductive system consists of unbranched vas deferens, an elongated seminal vesicle connected to a short and coiled ejaculatory duct, a round prostatic vesicle, and a small stylet housed in a deep antrum. The female system has a deep and tubular female antrum with curved cement pouches and a short vagina directed backwards and surrounded by the cement gland."
Behaviour.
Benthic, diurnals, because of its aposematic colors, it has no fear to crawl around to feed.
Feeding.
"Pseudoceros goslineri" feeds on various colonial ascidians.


Pat Hall

Beryl Patricia Hall, née Woodhouse (13 June 1917 – 26 August 2010) (cited in ornithological literature as B.P. Hall and in self-published works as Pat Hall), was a British ornithologist, associated with the Natural History Museum. She is best known for her work on African birds. She also wrote a book of whimsical poems with Derek Goodwin called the "Bird Room Ballads" (1969).
Pat grew up in Epson, Surrey, born in an upper-middle-class family. Her ambition was to study mathematics at Cambridge but she failed to pursue it due to opposition from her parents. Forced to spend several years at home, she took to watching birds and then decided to sign up for the Women's Legion in 1939. Her work involved teaching ambulance driving and precautions during Air Raids. She got engaged to John Hall, a lieutenant in the army who was posted in the Middle East. She was initially posted to South Africa and she transferred to Egypt in March 1941 allowing her to marry John.
After the war she returned to the UK and in 1947, following a failed marriage, she took up a position as a scientific associate at the bird room of the Natural History Museum. She obtained the job after meeting Sir Norman Kinnear who was a friend of her cousin Alfred Hughes. She then joined an expedition to southern and south-western Africa in 1949 along with James Macdonald and Colonel F. O. Cave. Working for half a year, they collected 1300 specimens of nearly 200 species of bird. She went on several self-funded expeditions in 1953 to northern Bechuanaland and another to Angola in 1957. She led the Harold Hall expedition to Australia based on her experience in arid zones in 1965.
She worked on a number of African bird groups including the francolins. Her major work was "An Atlas of Speciation in African Passerine Birds" (1970) in collaboration with R.E. Moreau. She also wrote two books based on her war years in Africa "What a Way to Win a War" (1978) and "A Hawk from a Handsaw" (1993). Along with Derek Goodwin, she also wrote a series of whimsical poems "Bird Room Ballads" which were based on their activities in the bird section of the British Museum.
Pat was a member of the Committee of the British Ornithologists’ Club from 1955 to 1964 and an Assistant Editor of the Ibis from 1971 to 1973. She received the Gill Memorial Medal and the Stamford Raffles Award in 1971 as well as a BOU medal in 1973. She was invited to preside over the 4th Pan African Ornithological Congress in 1976. A species named by Russian-born ornithologist Alexandre Prigogine (1913-1991) after her as "Hall's greenbul" ("Eurillas hallae") is now considered to be a melanistic specimen of "little greenbul".


Dorsal nasal artery

The dorsal nasal artery is an artery of the head. It is one of two terminal branches of the ophthalmic artery, the other being the supratrochlear artery.
Structure.
The dorsal nasal artery is a terminal branch of the ophthalmic artery in the superomedial orbit. It passes anteriorly to exit the orbit between the trochlea superiorly and the medial palpebral ligament inferiorly. First it gives a branch to the lacrimal sac. Then it bifurcates into a branch that anastomoses with the terminal part of the facial artery and a branch that travels along the dorsum of the nose. This latter branch also anastomoses with its contralateral pair and the lateral nasal branch of the facial artery.


Elizabeth King Ellicott

Elizabeth King Ellicott (1858–1914) was an American suffragist.
Biography.
Ellicott was born in 1858 to a wealthy Baltimore family. After studying at the Howland Institute, she returned to Baltimore. Several years later, she and several friends opened the Bryn Mawr School for Girls in 1885. That same group four years later donated $500,000 to Johns Hopkins University, on the condition that they allow women to attend the medical university. In 1894, she founded the Women's Literary Club and Arundel club in Baltimore. In 1900, the latter club would merge into the Maryland Federation of Women's Clubs, of which Ellicott was elected president of the board. That same year, she married William Miller Ellicott.
Six years later, after resigning from the board, she became involved in the suffrage movement. She organized the Equal Suffrage League of Baltimore out of the nearly defunct Livermore Equal Rights League. The league worked closely with the Maryland Woman Suffrage Association. The Baltimore League broke permanently from the Maryland League in 1910, when they submitted an equal suffrage bill to the Maryland General Assembly, which was quickly defeated. After the break, Ellicott formed a competing association, the State Equal Franchise League of Maryland, in 1911. The club began publishing "The New Voter", Maryland's first suffrage magazine. After suffering from ill health for years, she died of pneumonia and a subsequent heart failure on May 14, 1914. She left about $250,000 to many establishments. A large portion of the money went to establishing the Elizabeth King Ellicott Fellowship for the Political Education of Women at Goucher College.


Katrina van Grouw

Katrina van Grouw is a British science author, illustrator, and fine artist, best known for her illustrated natural science books "The Unfeathered Bird" and "Unnatural Selection" published by Princeton University Press. She has degrees in Fine Art and Natural History Illustration. Van Grouw is a self-taught ornithologist with an interest in comparative anatomy, evolution, and the history of the natural sciences.
Early life and education.
Katrina van Grouw was born in Pontypool, South Wales in 1965, adopted, and raised as Katrina Cook in Aylesbury, Buckinghamshire. (She became known by her current name after her marriage to Hein van Grouw, in 2009.) Van Grouw states that her prodigious drawing ability led to artistic hothousing during her school education which compromised her academic achievements.
She gained a BA in Fine Art, specialising in printmaking, from the University of Plymouth (at that time Exeter College of Art and Design) in 1990, and an MA in Natural History Illustration from the Royal College of Art in 1992 with a research thesis on bird anatomy.
Fine art.
In 1993 van Grouw moved to a cottage in rural Devon and began her career as a self-employed fine artist, specialising in large scale drypoints—a form of intaglio printmaking—of natural history subjects. She also taught adult education classes in drypoint, and lectured in printmaking and illustration to undergraduate students at the University of Plymouth, Chelsea College of Art and Design, and Falmouth College of Art and Design. She was an elected member of the Society of Wildlife Artists, held numerous open and solo exhibitions, and won several awards including the Birdwatch Artist of the Year Award in 1997 (black and white section) and 1998 (overall winner), the Wildlife Art Gallery Award in 1993 & 1996, and the PJC Drawing Award in 2014. From 1996 her subject matter and preferred medium changed to large graphite drawings of geological formations.
Fine art was put aside during the final push to write and illustrate "The Unfeathered Bird", and after its completion van Grouw found that producing illustrated books now “ticked all creative and intellectual boxes”.
History of natural history illustration.
During her education Katrina van Grouw developed a specialist interest in historical illustrated natural history publications and the printing techniques used to create them. John James Audubon's "The Birds of America", Robert John Thornton's "Temple of Flora", George Stubbs' "The Anatomy of the Horse", and the printing by Alecto Historical Editions of "Banks' Florilegium" in the 1980s were particularly influential.
Van Grouw has continued to write, consult, give talks and demonstrations, and national media broadcasts about historical natural history art. Projects have included selecting images and writing text for the British Library's Turning the Pages virtual book of Audubon's "The Birds of America"; appearing in Episode 1 of the BBC TV program "The Secret of Drawing" in 2005 hosted by Andrew Graham Dixon (again talking about "The Birds of America)"; and demonstrating intaglio printing in a short film about Sydney Parkinson, the artist on James Cook's "HMS" "Endeavour" voyage, for the British Natural History Museum. She was a freelance consultant for the Natural History Museum's 2011 edition of "The Birds of America" and fact checker for "Birds: The Art of Ornithology" (and "Great Birds of Britain and Europe") by Jonathan Elphick. Van Grouw regularly carries out identifications of birds depicted in historic Indian and Islamic paintings for Simon Ray and other London auction houses, and writes accompanying text for their sales catalogues. She has given frequent talks about printing techniques and their history in natural history publications at the Natural History Museum's libraries including the Rothschild Library at Tring and Rare Books Room at the NHM South Kensington, London.
In 2007 van Grouw was commissioned by Quercus to author "Birds" an illustrated history of birds in art, choosing to focus on the biographies of the artists and the stories surrounding the creation and publication of their works. She also sourced the images and drew up the preliminary designs for the book.
Ornithology.
Katrina van Grouw has been passionate about natural history and a keen birdwatcher throughout her life. She qualified as a bird ringer in the 1990s and took part in several long-term ringing expeditions in Africa, South America and the Shetland Islands, She was employed as resident bird ringer at Rutland Water Nature Reserve in 1998.
Her interest in the preparation of museum specimens began as a young child. As an undergraduate student she taught herself to prepare bird study skins, and to clean and assemble skeletons. During this time she formulated her plans to produce "The Unfeathered Bird", initially intended as an anatomy guide specifically for artists.
Her preparation skills and knowledge of birds led to her employment as a curator of the ornithological research collections (Bird Group) at the British Natural History Museum in 2003, initially full-time and then in a job-share arrangement with her husband, the Dutch ornithologist and bird breeder Hein van Grouw. Van Grouw states that she was prohibited by a senior manager from undertaking spare time commercial writing or illustration projects, which led to her resignation in 2010 in order to pursue her long-term ambition to create "The Unfeathered Bird", "leaving [her] utterly broken". Her husband remained at the museum in her place.
The Unfeathered Bird.
"The Unfeathered Bird" was published in 2013 - twenty five years after its conception. Originally intended to be an anatomy resource for artists, van Grouw was determined that it should accessible to a wide audience with interdisciplinary interests, and spent years seeking a suitable publisher that would allow her vision to be brought to life.
According to the author's autobiographic account given in her public lecture, "A Very Fine Swan Indeed: Art, Science, and 'The Unfeathered Bird"', her successful relationship with Princeton University Press began in 2010 with a chance meeting with the publishers' Executive Editor Robert Kirk in a pub during the British Birdwatching Fair.
One remarkable feature of the book is that it shows skeletons in animated postures as though they were alive and engaged in natural activities. The majority of the illustrations were drawn from skeletons that were cleaned and assembled by her husband at their home, leaving Katrina van Grouw free to concentrate on the illustrations and text. In the book's acknowledgments the author states, "no bird was harmed during the making of this book" before going on to give an exhaustive list of people who donated dead specimens which had died of natural causes, and of museum collections used.
"The Unfeathered Bird" was received with worldwide critical acclaim from art and science communities alike.
It's dedicated "To Amy" which was the name given to the Mallard skeleton van Grouw cleaned and assembled in 1987 and which sparked off the initial idea for "The Unfeathered Bird", leading one reviewer to describe it as "undoubtedly the best ever book to be inspired by a dead duck."
A second and greatly expanded edition of "The Unfeathered Bird" is currently in production.
Unnatural Selection.
The publication of Unnatural Selection in 2018 was timed to commemorate the 150th anniversary of the "Variation of Animals and Plants Under Domestication", by Charles Darwin. In the book's acknowledgments the author states that it was produced to thank her husband, Hein van Grouw "a domesticated animal nerd", for his help preparing the skeletons for "The Unfeathered Bird," combining his knowledge of selective breeding with her own interest in evolutionary biology. The dedication in the book reads, "To Husband, Naturally" and Hein van Grouw is referred to throughout the book simply as 'Husband'.
It was published by Princeton University Press, once again, and the size and format is consistent with "The Unfeathered Bird". In addition to the 80,000+ words of text, the book contains 425 illustrations by the author, who was also responsible for the design and layout of the entire book. It took six years to produce.
List of published works.
Books.
Author, Illustrator, and Designer
Author


Sporidia

Sporidia are result of homokaryotic smut fungi (which are not pathogenic), asexual reproduction through the process of budding.
Thus far, this has only been observed "in vitro"


Occipitofrontalis muscle

The occipitofrontalis muscle (epicranius muscle) is a muscle which covers parts of the skull. It consists of two parts or bellies: The occipital belly, near the occipital bone, and the frontal belly, near the frontal bone. In humans, the occipitofrontalis only serves for facial expressions.
Some sources consider the occipital and frontal bellies to be two distinct muscles. However, Terminologia Anatomica currently classifies it as a single muscle, and also includes the temporoparietalis muscle as part of the epicranius.
The occipitofrontalis muscle receives blood from several arteries. The frontal belly receives blood from the supraorbital and supratrochlear arteries, while the occipital belly receives blood from the occipital artery.
The occipitofrontalis muscle is innervated by the facial nerve.
Course.
The occipital belly originates on the lateral two-thirds of the highest nuchal line, and on the mastoid process of the temporal bone. Inserted into the galea aponeurotica, or epicranial aponeurosis, the occipital belly communicates with the frontal belly by an intermediate tendon. From the aponeurosis, the frontal belly is inserted in the fascia of the facial muscles and in the skin above the eyes and nose.
Action.
Assisted by the occipital belly, the frontal belly draws the scalp back, which raises the eyebrows and wrinkles the forehead.
Evolution.
In humans, the occipitofrontalis only serves for facial expressions. In apes, however, the head is not balanced on the vertebral column, and apes therefore need strong muscles that pull back on the skull and prominent supraorbital ridges for the attachment of these muscles.


Valdotriton

Valdotriton is a genus of extinct prehistoric salamanders. Its only known species is "Valdotriton gracilis" (also known as the Wealden newt). "V. gracilis" lived during the Late Barremian in what is now Spain. It was found in the Las Hoyas locality.
Description.
"V. gracilis" was a fairly small salamander, available specimens ranging from to in length, however no single specimen could decisively be determined to be an adult. In all specimens, however, the tail was longer than the torso.


Biomolecular condensate

Biomolecular condensates are a class of non-membrane bound organelles and organelle subdomains, specified by physical concepts that date back a long way. As with other organelles, biomolecular condensates are specialized subunits of the cell. However, unlike many organelles, biomolecular condensate composition is not controlled by a bounding membrane. Instead they can form through a range of different processes, the most well-known of which is phase separation of proteins, RNA and other biopolymers into either colloidal emulsions, liquid crystals, solid crystals or aggregates within cells.
History.
Micellar theory.
The micellar theory of Carl Nägeli was developed from his detailed study of starch granules in 1858. Amorphous substances such as starch and cellulose were proposed to consist of building blocks, packed in a loosely crystalline array to form which he later termed “micelles”. Water could penetrate between the micelles, and new micelles could form in the interstices between old micelles. The swelling of starch grains and their growth was described by a molecular-aggregate model, which he also applied to the cellulose of the plant cell wall. The modern usage of 'micelle' refers strictly to lipids, but its original usage clearly extended to other types of biomolecule, and this legacy is reflected to this day in the description of milk as being composed of 'casein micelles'.
Colloidal phase separation theory.
The term 'colloid' was coined by Wolfgang Ostwald and defined by Thomas Graham in 1861 to describe the behaviour of certain biological macromolecules (starch, albumin, gelatin, etc) and inorganic molecules as slowly diffusing components of cloudy liquid solution-suspensions that were blocked by semi-permeable membranes, while the physics of phase separation was described by Josiah Willard Gibbs in his landmark paper titled "On the Equilibrium of Heterogeneous Substances", published in parts between 1875 and 1878. Influenced by Willard Gibbs, important contributions were also made by Johannes Diderik van der Waals, who in 1890 published a treatise on the "Theory of Binary Solutions".
The concept of intracellular colloids as an organizing principle for the compartmentalization of living cells dates back to the end of the 19th century, beginning with William Bate Hardy and Edmund Beecher Wilson who described the cytoplasm (then called 'protoplasm') as a colloid. Around the same time, Thomas Harrison Montgomery Jr. described the morphology of the nucleolus, an organelle within the nucleus, which has subsequently been shown to form through intracellular phase separation. WB Hardy linked formation of biological colloids with phase separation in his study of globulins, stating that: "The globulin is dispersed in the solvent as particles which are the colloid particles and which are so large as to form an internal phase", and further contributed to the basic physical description of oil-water phase separation.
Colloidal phase separation as a driving force in cellular organisation appealed strongly to Stephane Leduc, who wrote in his influential 1911 book "The Mechanism of Life": "Hence the study of life may be best begun by the study of those physico-chemical phenomena which result from the contact of two different liquids. Biology is thus but a branch of the physico-chemistry of liquids; it includes the study of electrolytic and colloidal solutions, and of the molecular forces brought into play by solution, osmosis, diffusion, cohesion, and crystallization."
The primordial soup theory of the origin of life, proposed by Alexander Oparin in Russian in 1924 (published in English in 1936) and by J.B.S. Haldane in 1929, suggested that life was preceded by the formation of what Haldane called a "hot dilute soup" of "colloidal organic substances", and which Oparin referred to as 'coacervates' (after de Jong ) - particles composed of two or more colloids which might be protein, lipid or nucleic acid. These ideas strongly influenced the subsequent work of Sidney W. Fox on proteinoid microspheres.
Molecular biology.
In 1922, Hermann Staudinger refined the colloidal association theory of Thomas Graham by proposing that certain colloids were composed of high molecular weight polymers (chains linked by covalent bonds), which he termed 'macromolecules' to distinguish them from colloidal clusters of lower molecular weight molecules. So strongly held was colloidal association theory that even Emil Fischer, who had concluded that proteins are polypeptides formed by covalent bonds between amino acid units in 1906, initially refused to believe in the existence of high molecular weight polymers. Staudinger eventually received the Nobel Prize in 1953. Importantly, the discovery of high molecular weight macromolecular polymers cast doubt on the universality of colloidal phase separation in biology, despite the fact that individual polymers could still be observed to associate by clustering and phase separation to form colloids, liquid crystals, solid crystals or aggregates.
A far greater impact occurred when Frederick Sanger determined the amino acid sequence of Insulin and Linus Pauling, Robert Corey and Herman Branson correctly proposed the alpha helix and beta sheet as the primary structural motifs in protein secondary structure, while Max Perutz and John Kendrew analysed the 3D structure of myoglobin and later haemoglobin. These breakthroughs in protein structure determination led to a general focus of biologists on atomic-scale amino acid sequence- and 3D conformation-specific protein-protein interactions of a lock and key model type, usually between defined numbers of interacting subunits within a stoichiometric complex. Together with Staudinger's Nobel Prize in 1953 this new approach led to a reduced interest in biopolymers as colloids in biology, apart from their propensity to form solid crystals for structure determination by X-ray crystallography. Nevertheless, the fields of colloid chemistry and polymer physics continued unabated to characterise the non-stoichiometric interactions occurring during colloidal, liquid crystal and other phase behaviour of macromolecular polymers, particularly synthetic polymers developed for industrial applications.
Support from other disciplines.
When cell biologists largely abandoned colloidal phase separation, it was left to relative outsiders - agricultural scientists and physicists - to make further progress in the study of phase separating biomolecules in cells.
Beginning in the early 1970s, Harold M Farrell Jr. at the US Department of Agriculture developed a colloidal phase separation model for milk casein micelles that form within mammary gland cells before secretion as milk.
Also in the 1970s, physicists Tanaka & Benedek at MIT identified phase-separation behaviour of gamma-crystallin proteins from lens epithelial cells and cataracts in solution, which Benedek referred to as 'protein condensation'.
In the 1980s and 1990s, Athene Donald's polymer physics lab in Cambridge extensively characterised phase transitions / phase separation of starch granules from the cytoplasm of plant cells, which behave as liquid crystals.
In 1991, Pierre-Gilles de Gennes received the Nobel Prize in Physics for developing a generalized theory of phase transitions with particular applications to describing ordering and phase transitions in polymers. Unfortunately, de Gennes wrote in "Nature" that polymers should be distinguished from other types of colloids, even though they can display similar clustering and phase separation behaviour, a stance that has been reflected in the reduced usage of the term colloid to describe the higher-order association behaviour of biopolymers in modern cell biology and molecular self-assembly.
Phase separation revisited.
Advances in confocal microscopy at the end of the 20th century identified proteins, RNA or carbohydrates localising to many non-membrane bound cellular compartments within the cytoplasm or nucleus which were variously referred to as 'puncta/dots', 'signalosomes', 'granules', 'bodies', 'assemblies', 'paraspeckles', 'purinosomes', 'inclusions', 'aggregates' or 'factories'. During this time period (1995-2008) the concept of phase separation was re-borrowed from colloidal chemistry & polymer physics and proposed to underlie both cytoplasmic and nuclear compartmentalization.
Since 2009, further evidence for biomacromolecules undergoing intracellular phase transitions (phase separation) has been observed in many different contexts, both within cells and in reconstituted "in vitro" experiments.
The newly coined term "biomolecular condensate" refers to biological polymers (as opposed to synthetic polymers) that undergo self assembly via clustering to increase the local concentration of the assembling components, and is analogous to the physical definition of condensation.
In physics, condensation typically refers to a gas-liquid phase transition.
In biology the term 'condensation' is used much more broadly and can also refer to liquid-liquid phase separation to form colloidal emulsions or liquid crystals within cells, and liquid-solid phase separation to form gels, sols, or suspensions within cells as well as liquid-to-solid phase transitions such as DNA condensation during prophase of the cell cycle or protein condensation of crystallins in cataracts. With this in mind, the term 'biomolecular condensates' was deliberately introduced to reflect this breadth (see below). Since biomolecular condensation generally involves oligomeric or polymeric interactions between an indefinite number of components, it is generally considered distinct from formation of smaller stoichiometric protein complexes with defined numbers of subunits, such as viral capsids or the proteasome - although both are examples of spontaneous molecular self-assembly or self-organisation.
Mechanistically, it appears that the conformational landscape (in particular, whether it is enriched in extended disordered states) and multivalent interactions between intrinsically disordered proteins (including cross-beta polymerisation), and/or protein domains that induce head-to-tail oligomeric or polymeric clustering, might play a role in phase separation of proteins.
Examples.
Many examples of biomolecular condensates have been characterized in the cytoplasm and the nucleus that are thought to arise by either liquid-liquid or liquid-solid phase separation.
Nuclear condensates.
Other nuclear structures including heterochromatin and DNA condensation in condensed mitosis chromosomes form by mechanisms similar to phase separation, so can also be classified as biomolecular condensates.
Lipid enclosed organelles and lipoproteins are not considered condensates.
Typical organelles or endosomes enclosed by a lipid bilayer are not considered biomolecular condensates. In addition, lipid droplets are surrounded by a lipid monolayer in the cytoplasm, or in milk, or in tears, so appear to fall under the 'membrane bound' category. Finally, secreted LDL and HDL lipoprotein particles are also enclosed by a lipid monolayer. The formation of these structures involves phase separation to from colloidal micelles or liquid crystal bilayers, but they are not classified as biomolecular condensates, as this term is reserved for non-membrane bound organelles.
Liquid-liquid phase separation (LLPS) in biology.
Liquid biomolecular condensates.
Liquid-liquid phase separation (LLPS) generates a subtype of colloid known as an emulsion that can coalesce to from large droplets within a liquid. Ordering of molecules during liquid-liquid phase separation can generate liquid crystals rather than emulsions. In cells, LLPS produces a liquid subclass of biomolecular condensate that can behave as either an emulsion or liquid crystal.
The term biomolecular condensates was introduced in the context of intracellular assemblies as a convenient and non-exclusionary term to describe non-stoichiometric assemblies of biomolecules. The choice of language here is specific and important. It has been proposed that many biomolecular condensates form through liquid-liquid phase separation (LLPS) to form colloidal emulsions or liquid crystals in living organisms, as opposed to liquid-solid phase separation to form crystals/aggregates in gels, sols or suspensions within cells or extracellular secretions. However, unequivocally demonstrating that a cellular body forms through liquid-liquid phase separation is challenging, because different material states (liquid vs. gel vs. solid) are not always easy to distinguish in living cells. The term "biomolecular condensate" directly addresses this challenge by making no assumption regarding either the physical mechanism through which assembly is achieved, nor the material state of the resulting assembly. Consequently, cellular bodies that form through liquid-liquid phase separation are a subset of biomolecular condensates, as are those where the physical origins of assembly are unknown. Historically, many cellular non-membrane bound compartments identified microscopically fall under the broad umbrella of biomolecular condensates.
In physics, phase separation can be classified into the following types of colloid, of which biomolecular condensates are one example:
In biology, the most relevant forms of phase separation are either liquid-liquid or liquid-solid, although there have been reports of gas vesicles surrounded by a phase separated protein coat in the cytoplasm of some microorganisms.
Wnt signalling.
One of the first discovered examples of a highly dynamic intracellular liquid biomolecular condensate with a clear physiological function were the supramolecular complexes (Wnt signalosomes) formed by components of the Wnt signaling pathway. The Dishevelled (Dsh or Dvl) protein undergoes clustering in the cytoplasm via its DIX domain, which mediates protein clustering (polymerisation) and phase separation, and is important for signal transduction. The Dsh protein functions both in planar polarity and Wnt signalling, where it recruits another supramolecular complex (the Axin complex) to Wnt receptors at the plasma membrane. The formation of these Dishevelled and Axin containing droplets is conserved across metazoans, including in "Drosophila", "Xenopus", and human cells.
P granules.
Another example of liquid droplets in cells are the germline P granules in "Caenorhabditis elegans". These granules separate out from the cytoplasm and form droplets, as oil does from water. Both the granules and the surrounding cytoplasm are liquid in the sense that they flow in response to forces, and two of the granules can coalesce when they come in contact. When (some of) the molecules in the granules are studied (via fluorescence recovery after photobleaching), they are found to rapidly turnover in the droplets, meaning that molecules diffuse into and out of the granules, just as expected in a liquid droplet. The droplets can also grow to be many molecules across (micrometres) Studies of droplets of the "Caenorhabditis elegans" protein LAF-1 "in vitro" also show liquid-like behaviour, with an apparent viscosity formula_1Pa s. This is about a ten thousand times that of water at room temperature, but it is small enough to enable the LAF-1 droplets to flow like a liquid. Generally, interaction strength (affinity) and valence (number of binding sites) of the phase separating biomolecules influence their condensates viscosity, as well as their overall tendency to phase separate.


Gregor W. Yeates

Gregor William Yeates, publishing as GW Yeates (19 May 1944 – 6 August 2012), was a New Zealand soil zoologist and ecologist. He was "considered the world's leading authority in soil nematode ecology, a subject of economic and ecological importance."
Scientific career and contributions.
Yeates's PhD (under Wally Clark) and DSc were both at the University of Canterbury.
He spent most of his working life at Soil Bureau, a division of DSIR, which became Landcare Research. He published over 200 papers and described over 100 species in genera including , , Hemicycliophora, and Dorylaimida.
Holotypes of Yeates's are the earliest in the National Nematode Collection of New Zealand.
As a student he counted Adelie Penguins st Cape Royds 1964–65 and 1965–66.
Yeates's early work on nematodes in sand dunes represented some of the first detailed work on nematodes in non-agricultural settings, and 'representing some of the most detailed assessments of nematode communities ever conducted in natural environments.'
He was awarded a Nuffield Foundation Commonwealth Travelling Fellowship to study at Rothamsted in 1977–1978.
He conducted long-term work on CO2 enrichment in pasture.
He studied the New Zealand flatworm "Arthurdendyus triangulatus" in its native environment, supporting work in the United Kingdom where it became established as an invasive pest.
Family and civic life.
Yeates was the son of Massey founding staff member John Stuart Yeates. He and wife Judy lived in Upper Hutt and Palmerston North, with two children. He was elected to the Rimutaka ward of the Upper Hutt City Council (1973–1977) and the Hutt Valley Drainage Board (1973–1977). He was later involved with Te Manawa in Palmerston North and the Royal Society of New Zealand at both a local and a national level.


Iliopsoas bursitis

Iliopsoas bursitis is inflammation of a bursa (synovial sac) lying between iliopsoas muscle and hip joint, lateral to femoral vessels. Pain is experienced over the same area and made worse by extension of hip joint.


Redia (trematode)


Flagtail pipefish

"Doryrhamphus" and "Dunckerocampus", popularly known as flagtail pipefish, are two genera of fishes in the family Syngnathidae. They are found in warm, relatively shallow waters of the Indo-Pacific, with a single species, "D. paulus", in the eastern Pacific. Most of these pipefishes are very colourful, and are fairly popular in the marine aquarium hobby despite requiring special care and not being recommended for beginners.
Their habit of flashing the distinctly patterned tails during courtship and other displays have earned them their English popular name. Adults are highly territorial and usually live in pairs. They feed on tiny crustaceans and other small animals, and most species from the genus "Doryrhamphus" will sometimes act as cleaners.
Description.
"Doryrhamphus" have a maximum length of or less, with "D. janssi" being the only species that surpasses . Most species have a horizontal blue line along their body, and all have a whitish-edged tail that is marked contrastingly with black, red or yellow.
"Dunckerocampus" are more elongated and have a maximum length between , with "D. chapmani" being the only species with a maximum length below . Their tail is red with a whitish edge, and in some species there is a white or yellow spot in the center. All except "D. baldwini" (and a similar, but possibly undescribed species from the eastern Indian Ocean) have vertical red/brown and yellow/white stripes on their body.
Taxonomy.
Considerable taxonomic confusion exists in these genera, both because a number of scientifically undescribed species remain and some of the already described species are variable.
The first to recognise the species now placed in "Dunckerocampus" as worthy of a separate genus was the German ichthyologist George Duncker, and for this reason he coined "Acanthognathus" in 1912. However, unbeknown to him that name was preoccupied by a genus of ants. The replacement name "Dunckerocampus" honours Duncker.
Following a review in 1985, "Dunckerocampus" was generally considered a subgenus of "Doryrhamphus", but in 1998 it was recommended that "Dunckerocampus" again should be a genus, and in addition to the species formerly placed in it, it should include the newly described "D. boylei". When described in 2004, "D. naia" was also placed in this genus. Recent authorities generally recognise "Doryrhamphus" and "Dunckerocampus" as separate genera.
Species.
Species and genera follow most recent reviews of this group.


Microhypsibiidae

Microhypsibiidae is a family of water bear or moss piglet, a tardigrade in the class Eutardigrada.
It contains the following species in two genera


Aquila chrysaetos simurgh

Aquila chrysaetos simurgh is an extinct subspecies of the widespread golden eagle. Fossils are found in Crete; it was sometimes evaluated as a full species.
Ecology.
It lived during the Pleistocene in Crete with "Mammuthus creticus", the smallest mammoth known.


Adeona

Adeona is a genus of bryozoans in the family Adeonidae. A typical example is the Australian species "Adeona cellulosa" that forms large colonies with bifoliate sheets containing numerous holes (fenestrae).


Marsh harrier

The marsh harriers are birds of prey of the harrier subfamily. They are medium-sized raptors and the largest and broadest-winged harriers. Most of them are associated with marshland and dense reedbeds. They are found almost worldwide, excluding only the Americas.
Until recently two species were generally recognized: the marsh harrier ("Circus aeruginosus") and the African marsh harrier ("C. ranivorus"). The marsh harrier is now usually split into several species, sometimes as many as six. These are the western marsh harrier ("C. aeruginosus"), eastern marsh harrier ("C. spilonotus"), Papuan harrier ("C. spilonotus spilothorax" or "C. spilothorax"), swamp harrier ("C. approximans"), Réunion harrier ("C. maillardi maillardi" or "C. maillardi") and Madagascar marsh harrier ("C. maillardi macrosceles" or "C. macrosceles").
At the beginning of the 20th century, the marsh harrier was hunted to extinction in the United Kingdom. After being reintroduced from other regions, its population steadily increased until DDT threatened it, along with other raptors, in the 1950s and 1960s. Since, the population has slowly and steadily increased.
Species.
The western marsh harrier ("Circus aeruginosus"), often simply called the marsh harrier, breeds widely across Europe and Asia. It is migratory except in the mildest regions, and winters mainly in Africa. It hunts small mammals, frogs, fish, insects and birds, surprising them as it drifts low over fields and reedbeds. Its long legs allow it to pluck frogs and fish from the water mid-swoop.
The western marsh harrier is a typical harrier, with long wings held in a shallow V in its low flight. It also resembles other harriers in having distinct male and female plumages, but its plumages are quite different from those of its relatives. The male has wings with grey and brown sections and black wingtips. Its head, tail and underparts are greyish, except for the chestnut belly. The female is mainly brown with a cream crown and cream leading edge to her wings. It is 19-22 inches long and weighs 1-2 lbs.
The eastern marsh harrier ("C. spilonotus") breeds in the grasslands and wetlands of southern Siberia, northern Mongolia, north-east China, Manchuria and Japan, and migrates for the northern winter to South-east Asia, the Philippines and northern Borneo.
Like all marsh harriers, it favours open, wet environments, and is frequently seen drifting low over rice fields, interspersing long, watchful circling glides with two or three slow, powerful wingbeats. Two subspecies are recognised: "C. s. spilonotus" of east Asia, and "C. s. spilothorax", of New Guinea and the islands nearby, which is sometimes thought to be a separate species and is often called the Papuan harrier.
The swamp harrier ("C. approximans") at about 50 to 58 cm is slightly larger than "C. spilonotus", often a little darker, and has less heavily barred wings and tail. It is commonly found in suitable habitat anywhere in Australasia, particularly in the higher rainfall areas to the east, south-east, and south-west, of Australia and throughout New Zealand, but also in the tropical north of Australia and the island groups of New Caledonia, Vanuatu, Fiji, Tonga and the Society Islands. It is also known as the Australasian harrier or Pacific marsh harrier.
The Madagascar marsh harrier or Madagascar harrier ("C. maillardi") is found on the Indian Ocean islands of Madagascar, Réunion and the Comoros. It is sometimes split into two species: Madagascar harrier ("Circus macrosceles") and Réunion harrier ("C. maillardi).
The African marsh harrier ("C. ranivorus") is a distinct non-migratory species that has not usually been included as a subspecies of "C. aeruginosus". It inhabits southern and eastern Africa.


Richard E. Young

Richard E. Young (born August 20, 1938) is a teuthologist. He is an Emeritus Professor of Oceanography at the University of Hawaii's School of Ocean and Earth Science and Technology.
Education.
Young took a Bachelor of Arts degree at Pomona College in 1960, his Master of Science degree was taken at the University of Southern California in 1964 and his PH.D. was awarded in 1968 by the University of Miami, Institute of Marine Sciences.
Career.
He was a visiting Assistant Professor of Zoology at the Ohio Wesleyan University from September, 1968 to June, 1969. He was appointed as an Associate Professor of Oceanography at the University of Hawaii in 1973 and in 1983 he was appointed as Professor of Oceanography. He officially retired in 2001 but continued as an Emeritus Professor to the present.
His current areas of study are the evolution, systematics and functional morphology of cephalopods, and the ecological roles that cephalopods perform in present and past oceanic communities. His past work on cephalopods included bioluminescence, the ecology of the larvae and the ecology of midwater animals. He has most recently being studying the ecology of animals in the Mesopelagic Boundary Region. From 1996 up to the present he has been a major contributor on cephalopods to the Tree of Life Web Project.
Selected publications.
The following are some publications where Young is a co-author:
Taxa named.
The squid genus "Discoteuthis" was described by Young and Roper in 1969 with two species.


Laccosaurus

Laccosaurus is an extinct monotypic genus of temnospondyl amphibian, the type species being Laccosaurus watsoni.
"Laccosaurus" was named by paleontologist Sidney H. Haughton in 1925. "Laccosaurus" belongs to the family Rhinesuchidae. Fossils have been found in the Late Permian Beaufort Group of South Africa.


Michael Grumley

Michael Grumley (July 6, 1942 – April 28, 1988) was an American writer and artist.
Grumley was born in Bettendorf, Iowa. He attended the University of Denver, the City College of New York and the Iowa Writers' Workshop Grumley received a B.S. Degree with a major in Philosophy from the University of Wisconsin-Milwaukee on June 7, 1964.
He was a founding member of The Violet Quill. His partner, another founding member of the Quill, was Robert Ferro. He wrote a regularly appearing column "Uptown" for the New York Native. Grumley and Ferro are buried together under the Ferro-Grumley memorial in Rockland Cemetery, Sparkill, New York.
Following their deaths, the Ferro-Grumley Foundation, which manages their estate, created and endowed the annual Ferro-Grumley Award for LGBT fiction in conjunction with Publishing Triangle.
Cryptozoology.
Grumley was interested in cryptozoology, he was the author of a book on Bigfoot, titled "There are Giants in the Earth" the book was first published in 1975 with a later edition appearing in 1976. In the book Grumley concluded that anthropoid giants once roamed the earth, and that today there are still isolated survivors which he claimed are living in tunnels and caves.


C. Phil Palmer

C. Philip Palmer is a palaeontologist at the Natural History Museum in London. He has worked extensively on molluscs of various types including scaphopods, bivalves and cephalopods.


Ruddy treeshrew

The ruddy treeshrew ("Tupaia splendidula") is a treeshrew species in the family Tupaiidae. It is endemic to Borneo, the Natuna Islands and the Anambas Islands.
Habitat and threats.
The ruddy treeshrew occurs in the forests of Indonesia. It lives at lower elevations, never occurring over 500 meters above sea level. Although listed as Least Concern, the ruddy treeshrew is still threatened by habitat loss, due to causes such as logging. Due to this, its population is slowly decreasing.
Subspecies.
The ruddy treeshrew has 5 subspecies, widely distributed throughout Indonesia:


Troponin T

Troponin T (shortened TnT or TropT) is a part of the troponin complex, which are proteins integral to the contraction of skeletal and heart muscles. They are expressed in skeletal and cardiac myocytes. Troponin T binds to tropomyosin and helps position it on actin, and together with the rest of the troponin complex, modulates contraction of striated muscle. The cardiac subtype of troponin T is especially useful in the laboratory diagnosis of heart attack because it is released into the blood-stream when damage to heart muscle occurs. It was discovered by the German physician Hugo A. Katus at the University of Heidelberg, who also developed the troponin T assay.
Reference values.
The 99th percentile cutoff for cardiac troponin T (cTnT) is 0.01 ng/mL. The reference range for the high sensitivity troponin T is a normal < 14 ng/L, borderline of 14-52 ng/L, and elevated of >52 ng/L.
Background.
The troponin complex is responsible for coupling the sarcomere contraction cycle to variations in intracellular calcium concentration. Increased troponin T levels after an episode of chest pain indicates myocardial infarction. It was discovered by the German physician Hugo A. Katus at the University of Heidelberg. He also developed the troponin T assay. In patients with stable coronary artery disease, the troponin T concentration has long been found to be significantly associated with the incidence of cardiovascular death and heart failure, but it was 2014 before it began to be accepted as a predictor of who would later suffer acute myocardial infarction (heart attack).


Deep lingual vein

The deep lingual vein is a vein which drains the tongue.


Dentalium gouldii

Dentalium gouldii, common name the Gould tuskshell, is a species of tusk shell, a marine scaphopod mollusc in the family Dentaliidae.


Heteropia

Heteropia is a genus of sponges in the family, Heteropiidae, and was first described in 1886 by Henry John Carter. The type species by monotypy is "Heteropia ramosa" (Carter, 1886), which he first called "Aphroceras ramosa" in the very same publication.
Distribution.
GBIF with just 37 georeferenced specimens in this genus, shows it having perhaps a world-wide distribution. The Australian Faunal Directory shows as being found on/off the coast of Western Australia, in the IMCRA regions of Central Western Shelf Transition, Central Western Shelf Province, Northwest Province, and the Central Western Transition.


Gleba

Gleba (, from Latin "glaeba, glēba", "lump") is the spore-bearing inner mass of certain fungi such as the puffball or stinkhorn.
The gleba is a solid mass of spores, generated within an enclosed area within the sporocarp. The continuous maturity of the sporogenous cells leave the spores behind as a powdery mass that can be easily blown away. The gleba may be sticky or it may be enclosed in a case (peridiole).
It is a tissue usually found in an angiocarpous fruit-body, especially gasteromycetes. Angiocarpous fruit-bodies usually consist of fruit enclosed within a covering that does not form a part of itself; such as the filbert covered by its husk, or the acorn seated in its cupule. The presence of gleba can be found in earthballs and puffballs. The gleba consists of mycelium, and basidia and may also contain capillitium threads.
Gleba found on the fruit body of species in the family Phallaceae is typically gelatinous, often fetid-smelling, and deliquescent (becoming liquid from the absorption of water). It is formed on the exterior face of the cap or the upper part of the fruit body. The foul smell helps to attract insects that help disperse the spores. Chemicals that contribute to the odor include methylmercaptan and hydrogen sulfide.
In popular culture.
In the 2003 "Friends" episode "The One with the Lottery", Ross and Rachel's daughter Emma says "gleba" as her first word. At first, the characters, save Rachel, don't believe it's a real word, but Rachel gives them the definition from a dictionary.


Clathrina procumbens

Clathrina procumbens is a species of calcareous sponge from Australia.