#suchians

#Archovember Day 8 - Carnufex carolinensis

Effigia – Late Triassic (208-201 Ma)

It’s time for our second Triassic animal, a little bipedal reptile from the famous Ghost Ranch Quarry. Its name is Effigia, which means ‘Ghost,’ and there’s a little more to it than you might think.

We don’t know very much about Effigia itself. It was a member of the small, scurrying sort of reptiles. It lived during the last days of Pangea in what is today New Mexico. New Mexico was a land of extremes, sandwiched between the rich coasts and the brutal deserts of the ancient supercontinent. It was afflicted by arid dry seasons and unpredictable wet seasons. Effigia was a nimble opportunist of an herbivore, probably able to eat a variety of hardy plants and weeds. It lived a lot like a dinosaur, and sure looked like one.

This isn’t a dinosaur, by the way.

Effigia is a poposaur, which were archosaurs closely-related to crocodilians. Despite that, Effigia is ridiculously similar to a theropod dinosaur. It has two legs and a gracile shape, with a long neck and a long tail. What’s the difference? There are a few minute skeletal differences, but a big one is that Effigia has an extra finger—theropods had three fingers at the most. Poposaurs took on all sorts of different shapes, and a lot of them ended up looking like dinosaurs. Some were bipeds, sure, but others were four-legged tanks. Some of them were even aquatic. They were a really diverse group, but only stuck around during the Triassic, probably perishing during the extinction event at the end of the period. Why, though, other than the obvious answer of “Mass extinction?” It’s possible that dinosaurs just did what they did, but better.

Dinosaurs weren’t around for most of the Triassic period. Despite being the first period in the Age of Dinosaurs, the stars of the show didn’t show up until around the end of the Triassic. It would be more accurate to call the Triassic the Age of the Suchians. If we’re talking about broad diversity of body shapes and niches, suchians (that is, crocodilians and everything more closely-related to them than to dinosaurs) were the most diverse during the Triassic. 

The Triassic began right after the Permian extinction, the most devastating extinction event in the history of the earth. That meant a lot of free real estate in the global food web, and the suchians were more than happy to help themselves. Their diversity was almost comparable to that of the dinosaurs in the Jurassic.They came in all sorts of shapes and filled just about every role you can think of. This diversity was cut short at the end of the Triassic, and reduced to only a few groups. Dinosaurs showed up in the meantime, and, for one reason or another, were more adjusted to the environment. Especially once everything started dying.

As with most other extinction events, we don’t know exactly what happened 200 million years ago, but we can see its effects. All of the suchians bit it, except for crocodylomorphs (crocodiles and near-crocodiles). That’s the poposaurs, phytosaurs, rauisuchians, aetosaurs, prestosuchids, and plenty more. Big amphibians, which still hung on after the Permian extinction, disappeared. All but the smallest synapsids went extinct, with the survivors eventually becoming mammals. We lost the conodonts, a group of jawless marine vertebrates that looked kind of like eels. There are, of course, a few theories as to how this whole situation went down. We know for a fact that Pangea was breaking up during this time, and that probably caused a whole lot of catastrophic events. To me, the most likely answer is a combination of two of the leading theories:

Climate change: As the continents broke up and more of the land found itself next to rivers and seas, the deserts covering Pangea shrank and animals adapted to live there were unable to do so anymore. This wasn’t all bad, though, since it led to the explosion in diversity in the Jurassic period. Every mass extinction has a silver lining, except maybe the Permian. That one just kind of fucked the entire planet up for 50 million years.

Lots and lots of volcanic activity: The continents moving away from each other at the same time probably made the earth kind of upset.  That much volcanism would have destroyed local ecosystems. It also means pumping a lot of harmful gasses into the air and exacerbating climate change around the world. All it takes is one big eruption to knock the climate off-kilter. For example, when Mount Tambora erupted in 1815, the next year was so cold that farmers in the eastern U.S. woke up to frosty crops in July. Imagine that, but happening a whole bunch.

There is a third theory about an asteroid impact, but there’s no definitive evidence of an impact from around that time. This theory gets thrown out a lot with mass extinctions, but is pretty much baseless if we don’t have a crater. It’s why the K-Pg impact wasn’t taken very seriously for a long time, until we found the crater and learned it was at least one of the major factors in that whole situation.

Despite only living for a little while at the beginning of the Mesozoic, Effigia and its cousins aren’t just failed experiments, or versions of dinosaurs that weren’t good enough. Extinction is unpredictable and apathetic. It kills haphazardly, without reason. If things hadn’t gone the way they did, would suchians have ruled the Mesozoic? We know that dinosaurs were excellent at adapting and could make the most of very little. If that was never a necessity, would they have fallen to the wayside as crocodile cousins took over? Would we talk about dinosaurs the way we talk about poposaurs, an anecdote in the story of life, forgotten in favor of the animals that made it? Would suchians have eventually produced something like birds?

Personally, I don’t think so. Birds rely on so many adaptations that only theropod dinosaurs have. Maybe a branch of suchians would have developed a similar body plan and produced something like a bird, but who knows? Feathers are only found in the animals closer to dinosaurs, would we even know about feathers? That’s assuming we or anything as intelligent as us even shows up. The more you think about it, the more questions there are.