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Week 5 Power Poll: Archosauromorph Reptiles

You: “What?” Me: “Come learn, friends.”

Hello, it is I Zuzu, science power poll writer extraordinaire. For those who don’t know I am a Rutgers grad who is currently a Ph.D. candidate at future Big Ten Football Powerhouse USC, getting a Ph.D. in paleontology. The crazy thing is this will be the last science power poll I write as a Ph.D. candidate, next year I should be writing one of these as a DOCTOR. Writing this here publicly as part of my huge list of manifesting energy that I will actually finish when I want to. Anyway, the past few years I have done science-themed power polls related to my field. Links below if you’d like to check them out. This year I want to focus on a cool group of reptiles that you all are actually familiar to a degree, but never viewed them in the context of Cladistics before.

(Past power poll links: Dinosaurs, Non-dinosaur extinct animals, Marine tetrapods, Geologic time scale, Semi-aquatic tetrapods, Crocodilians, Major Evolutionary Milestones)

Cladistics: Evolutionarily classifying organisms based on measurable shared characters. Grounded in the assumption that organisms which share more characters with one another more recently diverged from a common ancestor. Thus, are more closely related to each other than to those they share fewer characters with. One of the foundations of modern Evolutionary Biology.

Clades are evolutionary groups in cladistics. Primates are a clade. Cats are a clade. There can be clades within clades. Apes are a clade within primates. Big Cats are a clade within Cats. Clades can go all the way down to a single species. Or be as big Mammals, or Vertebrates, and even the clade of all life. You cannot leave a clade once you’re in it, you can only create a more specialized clade within a broader clade. E.g. snakes are in the lizard clade, but they are specialized lizards and make up their own clade within.

So Archosauromorph reptiles, or archosauromorphs, are a clade. What we think of as “reptiles” are split into two major clades. Lepidosauromorpha and Archosauromorpha. The latter is derived from the word “Archosaur” which means “ruling reptiles.” Archosauromorpha is a broad clade that includes reptiles which are more closely related to (share a more recent common ancestor with) dinosaurs and crocodiles than to lizards and snakes. Lepidosauromorpha are reptiles which are more closely related to lizards and snakes than to dinosaurs and crocodiles.

Archosaurmorpha is a very cool group of reptiles that had many diverse forms in the past and actually still dominate the present in a way you wouldn’t realize. SO buckle up, you gon’ learn about some neat reptiles today.

Some primers with a visual aid— Archosaurmorpha is a clade that includes the clade Archosauriformes. Within Archosauriformers exists the clade of Archosaurs. Each of these clades include various groups of Archosauromorph reptiles. There are 3 types of Archosauromorphs described in this Power Poll— Non-Archosauriform Archosauromorphs (evolutionarily fall in the purple circle), Non-Archosaur Archosauriformes (the green circle), and Archosaurs (the blue circle). Note: The circles are not scaled to time or number of animals in them, just conveying the nesting of clades aspect. For example, Archosaurs has incredible diversity.

1. Ohio State Buckeyes— Non-Avian Dinosaurs

Dinosaurs are the most famous and magnificent archosaurs (and thus archosauromorphs), the word “archosaur” means ruling reptile, and boy did they rule. They reigned on Earth for 165 million years in the Mesozoic Era, that is truly an unfathomable time. Dinosaurs are a clade because they are defined by a suite of characters that are unique to them compared to other archosaurs. They did kind of get got 66 million years ago, but avian dinosaurs continued their legacy and very successfully. No one shades a dinosaur. Ohio State is very much operating like dinosaurs in their prime.

2. Penn State Nittany Lions— Birds (Avian Dinosaurs)

Yes, birds are reptiles if you define a reptile as an Archosauromorph or Lepidosauromorph (together making the clade of Sauropsids) which most paleontologists do. Birds are a clade within the clade of Dinosauria, which means they are archosaurs. I know Penn State fans might be disappointed at getting animals as basic as birds in this power poll, but hear me out. Birds are amazing. Not only are they living dinosaurs, but they survived the mass extinction that killed the non-avian dinosaurs and a bunch of other animals, and they are the second most speciose and diverse vertebrate group on the planet. They are an unyielding success story. Penn State is good. We may all lament that the way we lament giving credit to birds for what they’ve done in life, but... it’s reality.

3. Michigan Wolverines— Crocodilians

Crocodilians are really amazing. They are a remnant of a once great dynasty of archosaurs called Crocodylomorpha, which was in an even broader group of archosaurs called Pseudosuchia. Living crocodilians constitute only 24 species of crocodiles, alligators, and caimans, and are very different from most of the great clade they belong to. They are highly derived compared to their extinct family members, which means they are quite different from the ancestral state they share with their other relatives. Crocodilians have just not been what they used to be for quite some time, but they are still really impressive animals, after all, they are alive. They survived two mass extinctions and major climate change. Holding their own and flourishing in the modern world. There is a Michigan analogy in here somewhere I think.

4. Minnesota Golden Gophers— Pterosaurs

Pterosaurs were the first flying vertebrate animals and a very successful archosaur group that spanned the Late Triassic to the end of the Cretaceous when the asteroid hit. They created a wing by elongating their wrist bones and super elongating their 5th digit (the pinky) to fly. Pterosaurs ranged from the size of a songbird to the size of a giraffe. People commonly mischaracterize pterosaurs as dinosaur, but they’re not! Though as archosaurs they are certainly close, in fact they are the sister clade to dinosaurs which means both pterosaurs and dinosaurs share a more recent common ancestor within archosaurs than they do with other archosaurs. Minnesota is a good team this year. They may not be a dinosaur, but they get to share the spotlight with the other Big Ten powers.

5. Maryland Terrapins— Euparkeria

Euparkeria are archosauriformes that are just outside of the archosaur clade. As such they share a lot of the same characteristics as archosaurs, but not all of the ones required to be an archosaur. It would have resembled a slender high walking crocodilian with the potential for bipedalism given that their hind legs were longer than their front legs. Euparkeria being close to archosaurs is not too different from Maryland being close to consideration as a very good Big Ten team. Like the archosaurs which rank above.

6. Iowa Hawkeyes— Phytosaurs

Phytosaurs are archosauriformes from the Late Triassic and they are remarkable for having done the “crocodile shape” before crocodiles did. At first glance you’d certainly call a phytosaur a crocodile, but if you looked closely at the head you’d see that their nostrils were up near their eyes instead of the tip of the snout as in crocs. Also, they were even more heavily armored than crocodilians. Phytosaurs are cool animals, and they were incredibly widespread during their prime. They just don’t get the attention as crocodiles for living the same lifestyle millions of years before them (but crocodiles also did it better). We may have voted Iowa 6th, but who is actually thinking about anything great for Iowa this year? And they’re just... not as good as the truly good teams.

7. Wisconsin Badgers— Rauisuchians

Rausuchians may not actually be in one clade with a single shared common ancestor among them (this is called paraphyletic, in contrast with the clades as I’ve been referring to which are also called monophyletic groups), but regardless they are certainly all archosaurs. They are in the same broader family as crocodilians and other croc relatives, called Pseudosuchia. Many Rauisuchids superficially resembled what many people think of as dinosaurs. They independently evolved upright legs underneath their body and some were even bipedal. They were fearsome, dominant Triassic predators, but sadly like many of the groups mentioned in this article, they died out, but after having success! Wisconsin has also had its run. So what if they’re a little meh now? They’ll bounce back. Crocodylomorphs certainly did.

8. Illinois Fighting Illini— Tanystropheids

Tanystropheids, semi-aquatic archosauromorphs of the Triassic, were some of the goofiest animals to ever exist if you ask me. The craziest members were called Tanystropheus and these were 20 foot long reptiles that had stiff, absurdly long necks that were longer than their bodies and tails combined. However, goofy or not these strange animals were doing something right because they lasted for like 45 million years. Surprisingly. Illinois is 3-1. I mean they’re a flawed team, but like Tanystropheids they’re doing something surprisingly right in their 2nd year under Bret Bielema to earn that record.

9. Purdue Boilermakers— Aetosaurs

Aetosaurs were Late Triassic (?)herbivorous(?) tank crocs. They were in the group Pseudosuchia (all the croc relatives) and were heavily armored and widespread. Aetosaurs went through many variations of interpretation. Their first fossils were thought to be fish scales, then when more were found it was thought they were semi-aquatic scavengers like crocodilians. Now we know them as fully terrestrial and at least omnivorous. Aetosaurs went through iterations of interpretation for paleontologists the way Purdue has given iterations of interpretation for the quality of the team for their fans this season. Bad... Medicore... Not terrible...

10. Michigan State Spartans— Erythrosuchids

Look at these idiots. Erythrosuchids were cool though, they’re archosauriformes that evolved shortly after the End-Permian Mass Extinction and became some of the biggest land predators of their time. They were essentially walking mouths, with short necks, and a mostly upright posture. The largest member of the clade was called Erythrosuchus and could grow around 15 feet long. They were successful Triassic predators, but would eventually be supplanted by more successful, less absurdly proportioned archosaurs like Rauisuchids. Like how Michigan State was replaced as a top Big Ten team with other top Big Ten teams.

11. Indiana Hoosiers— Azendohsaurids

Azendohsaurids were neat animals. Herbivorous archosauromorphs with long necks, and some, like the pictured Shringasaurus, possessed head ornamentation. They were kind of like discount sauropods (the long-necked plant-eating dinosaurs). They evolved to occupy a similar ecological space in the Middle Triassic, whereas dinosaurs would evolve in the Late Triassic. Azendohsaurids did the long-neck herbivore thing too, but are often forgotten about and not nearly as popular as sauropods. Kind of like Indiana who is not... so bad this year, 3-1. I guess. But I am certainly not thinking of them.

12. Rutgers Scarlet Knights— Protorosaurus

Protorosaurus is considered one of the earliest archosauromorphs, existing in the late Permian, the time period which preceded the most major mass extinction ever, and would have superficially resembled a monitor lizard with an elongated neck. Its existence prior to the Triassic and Archosauromorphs flourishing past the extinction signifies that Archosauromorphs were well-suited to survival. Protorosaurus is one of the earliest described fossil animals having been described in 1710 as a crocodile. But it is not! Kind of like how Rutgers was hyped up to totally upset Iowa, but then didn’t.

13. Northwestern Wildcats— Rhynchosaurs

Rhynchosaurs are small to medium sized, stocky herbivorous archosauromorphs whose premaxillae, the bones that make up at the front-most part of the snout, formed a beak-like structure. They also probably had strong jaw muscles for chewing vegetation. They were globally distributed at their height in the Middle Triassic. I honestly have no idea how to relate Rhynchosaurs to Northwestern, but they were bleh and boring which is how I feel about Northwestern most times.

14. Nebraska Cornhuskers— Trilophosaurids

Trilophosaurids were pretty lizard-y looking archosauromorphs. They were herbivorous with a thick skull, no teeth at the front of their snout (probably had some type of beak) and uniquely lack one of the holes in the skull that is a defining feature of other reptile groups. They are in the broader clade of non-archosauriform archosauromorphs called Allokotosaurians which means “strange reptiles.” Trilophosaurids were certainly strange. Like it is so strange (and funny) how bad Nebraska is.

Okay that’s it. Sweet lord, these are a lot of work to write.