Interesting Animals That Roamed The Earth Before Humans

The first undisputed signs of life began nearly 3.4 billion years ago, and ever since then, life has drastically evolved in forms and factors that are unlike anything we see on earth today. From giant land scorpions to extinct crocodiles the length of a school bus, explore interesting animals that walked (or swam) the earth long before humans.

Usually, most modern species of scorpions are smaller than the size of an average human hand. It is also relatively harmless, (save for a few species, which has very toxic and potentially lethal venom).

However, if you were to travel back in time to the Carboniferous Period, roughly 360 million years ago, you might just be unlucky enough to stumble upon Pulmonoscorpius kirktonensis – a giant land scorpion that was almost half as long as an adult human. Measuring in at over 2.5 feet, it probably killed its prey by ambushing it and then repeatedly stabbing it with its stinger. And just like its modern-day relatives, Pulmonoscorpius was probably venomous. Palaeontologists also estimated that it had relatively good eyesight thanks to its abnormally large eyes.

Primitive earth had an abundant plant life. The very first gymnosperms such as primitive cycads, horse-tails and club mosses thrived in the humid atmosphere of primitive earth. As a result, the oxygen concentration in the atmosphere was higher than today’s estimates, which in turn directly affected the size of prehistoric insects. Like Pulmonoscorpius, other prehistoric insects such as Meganeura (ancient dragonflies) and Arthropleura (ancient millipedes) also grew to gargantuan sizes due to the higher concentration of oxygen in the atmosphere.

In 1977, Simon Conway-Morris, a British Paleontologist stumbled upon a very odd, thumb-sized fossil collected from the Canadian Rockies. Initially, Morris speculated the fossil to be an annelid worm, similar to leeches and earthworms. It had seven spikes that would have been used as its “feet” and seven tentacles that waved around on its back. He named the creature Hallucigenia, due to its bizarre, and almost dream-like appearance.

Conway-Morris’s model of the creature was very controversial, however, it managed to be relevant up until the year 1991. By then, Chinese researchers had stumbled upon a similar fossil, named Microdictyon, which had plate-like scales instead of the seven spikes which Hallucigenia had. The researchers were able to deduce that the tentacle-like structures on the back of Hallucigenia were actually feet. So, for more than a decade, the scientific community was looking at Hallucigenia’s fossil upside down.

Even today, nearly 50 years after the discovery of this fossil, new discoveries are being made. Just recently, scientists have found the location of its head after examining its fossil in an electron microscope. Hallucigenia wears its name appropriately – it is still one of the weirdest creatures to be found till date.

Saber-Toothed Tiger
Today, big cats such as lions and tigers are the apex predators in almost all known terrestrial food chains. But 10,000 years ago, the plains of North and South America were home to the Smilodon or the saber-toothed tiger. S. populator was the largest of the species, weighing in at over 400 kgs. Also, they are much more burly than most other extant big cats such as the Bengal Tiger.

One of smilodon’s characteristic feature is the very long, dagger-like canines. Its teeth were so long that it protruded out of its mouth by a significant margin. It even had an incredibly wide gape to accommodate those fangs – opening its mouth up to 120 degrees, which would have been quite an impressive and menacing sight if it was alive today.

However, its canines were slender, blade-like, and rather fragile. So, it was more adapted for precision movement such as slicing, slashing and stabbing. Moreover, an extremely wide gape meant that the animal had a lower bite-force, this meant that its bite force was not proportional to its body size. Consequently, the bodies of these animals became more stocky and robust for immobilizing prey.

These big cats were specialized in taking down large mammals such as extinct bison, giant ground sloths and even juvenile mammoths. However, their prey started to die out and was replaced by smaller and more agile prey such as the ancestors of deer. As these apex predators were unable to adapt to these new prey, the population started to decline and eventually became extinct.

Humans belong to the family Hominidae, (also called as the great apes) and we are the only surviving member of this species today. But nearly nine million years ago, Asia was home to one of the biggest primates to ever walk the earth – Gigantopithecus blacki.

This gigantic great ape towered over 10 feet in height and weighed between 550-600 kgs, which makes it almost 3-4 times heavier than modern gorillas. However, scientists have theorized that it is more closely related to modern orangutans after analyzing its morphology. But not much else is known about this great ape as fossil evidence is limited to just a few teeth and fragments of a jaw bone.

When it was alive, its habitat consisted of a mosaic of savannah and forested areas. Analysis of its teeth implied that it subsisted purely on a diet of fruits and bamboo shoots, just like modern day gorillas. However, its habitat shrunk due to climate change and it was unable to adapt itself due to its huge size and strict selection of diet. The last of Gigantopithecus died out roughly 100,000 years ago.