Secretion is the process of elaborating, releasing, and oozing chemicals, or a secreted chemical substance from a cell or gland.In contrast to excretion, the substance may have a certain function, rather than being a waste product.ecretion is the process of elaborating, releasing, and oozing chemicals, or a secreted chemical substance from a cell or gland.
The oldest shark fossils. The oldest fossilized evidence of prehistoric sharks comes from shark-like scales that date to 455 million years ago during the Ordovician Period, in Colorado. Some paleontologists do not agree that these scales are sufficiently shark-like to pronounce them sharks.
Identification of Fossil Goblin Shark Teeth (Scapanorhynchus texanus): Identification of the Gobline Shark: Scapanorhynchus texanus. S. texanus are the most common Goblin shark tooth found in Cretaceous sediments in the Eastern U.S. They can easily be confused with the smaller sand tiger sharks. Diagnostic characteristics include: 1  Anterior teeth are heavily striated (grooves running up the enamel). 2  Striations continue onto the root in anteriors and many laterals. 3  The roots have a deep nutrient groove in them (notch in the center). 4  Many of the teeth have one or two cusplets.