Strange Creatures Who Roamed The Earth Before The Dinosaurs

If you asked most people to name the oldest forms of life that have existed on Earth, it is likely the first response you'll get back are dinosaurs. Yes, dinosaurs are old. Britannica tells us that they thrived during the Mesozoic Era between 252.2 and 66 million years ago. They ruled for a long time and a long time ago.

Mesozoic as a word is from Greek which translates to "middle life." Just the term alone implies that there was life before the dinosaurs. Indeed, before the Mesozoic there was the Paleozoic Era, which means "ancient life." To make an analogy with operating systems, if modern life and the dominance of mammals (Cenozoic Era) is Life 3.0, and the dinosaurs were Life 2.0, then what was Life 1.0?

The Paleozoic, Mesozoic, and Cenozoic (our era) are divided into geologic periods. The Paleozoic for example is split into six periods covering events from 541 to 252 million years ago. It starts with the Cambrian period when life greatly diversified and evolved in the seas. As the Paleozoic progressed into new eras life moved onto land, finally coming to a close with the disastrous Permian extinction which killed 90% of life on Earth. In those 289 million years of Life 1.0, natural selection and evolution produced some strange creatures that would fit more into a science fiction or fantasy novel than in animal documentary today. Let's take a look at some of them.

The top predator of the Cambrian seas was an over three-foot-long shrimp-like creature called Anomalocaris. As National Geographic describes, this animal featured a flattish body with undulating lobes that propelled it through the water. It spotted prey with two periscope-like eyes and seized it with two spiked claws that it would use to thrust the meal into a squarish mouth. The mouth itself did not have teeth as we know it today. Nature describes the orifice as having "tooth-like serrations."

While scientists have known that Anomalocaris was a top predator, it was only in 2011 that they learned its full effectiveness as a hunter. Fossils in Australia discovered in the Emu Bay Shale, known for preserving soft body parts, show that Anomalocaris had exceptional eyes. It had hexagonal lens on each eye, which is the standard set for the arthropods (insects and crustaceans) to which it is related. What is more, Anomalocaris had over 16,000 lenses on each eye and possibly higher. Paleontologist John Paterson of the University of New England in Australia who had been one of those who made the discovery commented to Nature, "This is a lot [of lenses]. The common housefly has only 3,200 and most ants have fewer than 1,000." Dragonflies have up to 28,000 lenses in each eye — and extraordinary eyesight — but they are according to Paterson, "the freaks of the arthropods."

Hallucigenia is regularly touted as the weirdest animal known to science. National Geographic tells us it was given its name in 1977 by the British paleontologist Simon Conway-Morris because of what he called its "bizarre and dream-like quality." And once you see this pencil-like worm with seven tentacles (with mouths) and seven spines, you'd probably agree that Hallucigenia belongs in a Pink Floyd movie.

Hallucigenia was small, up to 1.9 inches in length, and lived in the Cambrian seas. Because of its strangeness, more information about it is hard to fathom, but scientists have given it the post-doctoral try. For example, one problem was trying to figure out where its head was. In 2015, however, there was a breakthrough when researchers found what seemed to be a little set of circular teeth indicating that they at last found the head of Hallucigenia. As one of the researchers from the University of Cambridge, Dr. Martin Smith, was quoted saying, "The early evolutionary history of this huge group is pretty much uncharted." This is well stated, considering that there was so much trouble figuring out which side of Hallucigenia was up.

Dunkleosteus was an ancient armored fish that would give anybody nightmares. The Cleveland Museum of Natural History, which has the best preserved skeletons of this predatory armored fish, notes that it reached up to 20 feet in length and had self-sharpening bone protrusions that were neither fang nor tooth, but something far more frightening. Basically, imagine a giant fish with a guillotine at the end that would laugh at a barracuda.

There is little doubt that Dunkleosteus was not the peaceable type. It certainly wasn't a picky eater. According to the BBC, fossilized remains show that it ate sharks, rays, and was even its own kind. It also seemed to suffer from bowel troubles since fossils of it are often shown with semi-regurgitated remains. That aside, there are details about this ancient monster that we usually don't get from the fossil record. First, fossilized pigments show that Dunkleosteus was probably darkly colored on the top and silver on the bellow. Second, Dunkleosteus may have been one of the first fish to exist in different sexes.

The Carboniferous and Permian Periods, from about 350 million years ago, had an environment different from Earth today. As explained by "Life: the Science of Biology," oxygen levels on earth were about 50% higher. This allowed for the development of mega-insects. And there was no bigger insect than Meganeuropsis.

Meganeuropsis was a dragonfly, and from its fossils, it looks like one that you might see in your backyard today, though a touch bigger. According to Harvard Magazine, one species of Meganeuropsis from the Permian had a wingspan of two and half feet. The University of Nebraska — Lincoln, estimates its weight to be about a pound — that is, about the weight of a crow. It is likely that Meganeuropsis feasted on other insects in the air or preyed on small amphibians from the ground. The insect, however, has been debated, since, with a modern dragonfly, the way oxygen diffuses through its body gives it an upper size limit. This had led to support for theories about increased oxygen levels during these time periods.

By the end of the Paleozoic, life had colonized the land and had grown in diversity. One of these strange land creatures was the therapsid, Estemmenosuchus. What is a therapsid, you ask? Therapsids were a kind of reptile that lived during the Permian and into the Mesozoic Era, according to Britannica. This is the lineage of animals that gave rise to the mammals. These animals were known to be one of the first groups to have a diversity of teeth — incisors, canines, molars, and so on. 

Estemmenosuchus was no exception. "The Origin and Evolution of Mammals" describes it as having large saber-like canines. It was also large, being about the size of a small car, and weighed nearly half a ton. The funny thing is that at least according to "Prehistoric Giants," scientists can't quite agree if this creature was a herbivore or carnivore. Its canines and sharp incisors say it could hunt, but it also had a robust body form that seemed perfect for digesting plants. "Beasts Before Us" splits the difference and asserts Estemmenosuchus ate both plants and meat, making it an omnivore. Yet the strangest feature of Estemmenosuchus is that its face and head had a pattern of bony ridges or horn-like protuberances that seemed to explode outward in all directions. It is speculative, but these protuberances could have been used for defense, display, or contests of domination, like head-butting.

One of the main items on Inostrancevia's menu may have been Scutosaurus. Despite the sound of the name, Scutosaurus was not a dinosaur. Rather, it belonged to a class of animals termed by "Cowen's History of Life" as "parareptiles" being related to anapsid reptiles such as tortoises and turtles (via Nature). Scutosaurus was the size of a hippo and armored with bony plates for protection. This was probably a strong defense against the saber teeth of the gorgonopsians. This animal was also a herbivore, as described by the "Encyclopedia of Dinosaurs and Prehistoric Life," with its teeth designed for chewing as well as a (probably) large gut for digestion of plant matter. Aside from the bony plates, older scutosaurus as well as any of its kindred group called pareiasaurs, had horned projections in and about the face. It is supposed that these developed not only for defense, but also possibility for use in mating competitions of dominance.

Scutosaurus disappeared completely with the disaster at the end of the Permian.

While the Age of Dinosaurs is considered to be the Mesozoic Era — composed to the Triassic, Jurassic, and Cretaceous periods (via USGS) — dinosaurs did not immediately dominate life right after the mass extinction that ended the Paleozoic Era. According to National Geographic, dinosaurs first evolved during the late Triassic period. Millions of years elapsed during the very early Mesozoic before dinosaurs. This gave rise to some strange creatures, and one of them is the flying reptile Sharovipteryx.

"Triassic Life on Land" tells us that this animal is known from one skeleton which shows a 9.5 inch body of a reptile like creature. What made it most unique is that it had a membrane connected from the rear part of the body to the back legs. This presumably was to allow sharovipteryx to fly or glide. Just how it did that is explained in "The Age of Dinosaurs in Russia and Mongolia": it would glide using the rear membrane with its long tail serving as a counterweight. However, as with much of paleontology, better corroboration is needed with further fossil findings.