Introduction:
Arizonasaurus, meaning Arizona’s Lizard, was not actually a Dinosaur or a Lizard. I am pretty sure what Dinosaur comes to mind when you see a sail-backed reptile, it is the Ouranosaurus!! I am kidding!! I am sure Spinosaurus comes up on your mind but this is not even a Dinosaur and it is not even close to Spinosaurus, by time or by family tree. Arizonasaurus is a kind of terrestrial crocodile which became prominent in the Triassic Period.
This is one of the more bizarre forms a crocodilian family has adapted to and it is not alone in it’s family tree but this one is also one of the most complete fossil finds ever. Now, without any further delay, let’s learn what is this crocodilian in depth!
Discovery:
Arizonasaurus was discovered in, can you guess the location?? It’s in the name already, the USA‘s state of Arizona. Specifically saying, the Moenkopi Formation of Arizona which is full of Triassic Period aged rocks. The species was named by Samuel Paul Welles in 1947 and later on, a fairly complete skeleton was discovered in 2002 by Sterling Nesbitt. Not many fossils have been found after that and so we have to go off a part of top jaw and some teeth from 1947 but in 2002, a fairly complete but fragmentary skeleton was found and when compared with the previous find, they were the finds of the same species and we have a clearer picture of this crocodilian.
Biology:
Arizonasaurus was a terrestrial crocodilian which had a sail made of tall neural spines and it belonged to a family called Ctenosauriscidae which consists of similar genera like the Arizonasaurus. It grew up to 3m (10 ft) long and half a meter (1.6 ft) tall. It was a fairly decent sized crocodilian for Triassic Period and the presence of poposauroid in the early Middle Triassic Period suggests that the divergence of birds and crocodilians occurred way before than paleontologists thought.
One thing I find fascinating about Triassic is the very weird and different kinds of reptiles evolving at this time. Like look at Arizonasaurus itself, I mean, look at how cool it looks. A crocodile walking on 4 legs like a lion and a huge on the back like that of a Spinosaurus. It cannot go any cooler than this. Arizonasaurus had a spine before Spinosaurus but after Dimetrodon. I should make a post about Dimetrodon soon.
But Arizonasaurus is not the only member of the Ctenosauriscids and there are many more genera in this family group. Let’s take a look at some of the Ctenosauriscids, which are Xilousuchus, Hypselorhachis, Ctenosauriscus, Bromsgroveia and a Waldhaus taxon. Waldhaus taxon is basically researched to be a separate genus of animal but not described or published yet and so we do not know the name of it essentially. Ctenosauriscus is the genus and the namesake of the Ctenosauriscidae family. And this family evolved from Poposauroidea clade. Ctenosauriscidae genera, all of them, have some sort of sail structure and a crocodilian.
I find it amazing how one family group of reptiles diversified so quickly in just one time period and not only that but Triassic Period is also one of the smallest time period when compared with Jurassic and Cretaceous Period. Triassic Period is so unique and had an explosion of all sorts of lifeforms but not a lot of people know about this. Not a lot of people know how unique and cool Triassic Period is.
Ctenosauriscids from the Middle Triassic allowed the distribution of Triassic fauna to be widespread across Europe, North America, Asia and Africa. The fauna of the Moenkopi Formation represents a stage transitional fauna between the faunas of older and younger age. The weather in Middle Triassic could have been hot and arid which would cause them to have larger sails for thermoregulation. The sail would allow for body temperature change allowing for more of an active lifestyle as a carnivore.
Q&A:
Is Arizonasaurus related to Spinosaurus?
I was already guessing this would be most asked question and the answer is No. No, Arizonasaurus was not related to Spinosaurus in any shape or form or even by family grouping. Arizonasaurus was a part of the larger division of Archosauria, the Pseudosuchia which were more like distant cousins to the actual Crocodyliforme line and they did look very Crocodilian in nature and they were more lighter in build and stood more straight than splaying position like the crocs allowing them to be more nimble and agile in movement and also allowing them to hunt more terrestrial species. Spinosaurus was a dinosaur which is from a very different and hugely diverged line of Archosauria and they could not be any further apart. Dinosaurs are like distant relatives to Pseudosuchia and during the Triassic Period, Dinosaurs got the upper hand and became the dominant species on Earth.
The only reason this question comes up is because of spined-sail on both of these which makes it seem related but not. It is a common feature seen in many prehistoric animals to have a spined-sail but that does not mean they are all closely related to each other and this is what is called Convergent Evolution where one feature of a certain animal is shown to be replicated in another animal of an entirely different group. That is what between these 2 because the sail feature was so useful that happened in different times and in different animal groups. Remember, Arizonasaurus lived during the Triassic Period while Spinosaurus lived in the Cretaceous Period and there is a huge difference in family tree for them to be related in anyway.
What did Arizonasaurus eat?
Arizonasaurus was a carnivore of course and so it would hunt down any living animal that would fill it up. I am probably guessing what was on the menu for it and the menu had some amphibians of a certain group called Temnospondyls, like Eocyclotosaurus, Quasicyclotosaurus, Wellesaurus, Vigilius, & Cosgriffius as well as some herbivorous reptiles like Ammorhyncus and Anisodontosaurus. Also, small lizards, lungfish and as well as some freshwater sharks were included in the menu as well. Do let me know down in the comments if you would like to see blog posts of the named animals as well.
What does the name Arizonasaurus mean?
I mean, it is pretty simple really, just re-read the name and you maybe able to figure it out. Yes, the name literally means the Lizard of Arizona, the state of Arizona of USA in which it was found. Sometimes paleontologists give super unique names while sometimes they do this. There are a lot of examples of such naming styles but yeah. ‘Saurus‘ means ‘Lizard‘ in Latin and many times it would appear in names that are not Dinosaurs but it is not wrong either as it does not have a name yet but it certainly does make it confusing.
Where did Arizonasaurus live?
Hmm…I guess you should know the answer by now. Yes, the Arizonasaurus lived in the state of Arizona, USA! But the Arizonasaurus did not know it was an American citizen back in the Triassic Period as it lived, hunted, drank water from rivers and ponds, sunbathed and slept. Who knew Arizonasaurus would end up in Arizona state and maybe, even if it was found a bit to the North, it might have been called Utah-saurus. And yes, I checked and there is no Utah-saurus, instead we have Utahraptor. Let me know in the comments if you want a post about Utahraptor.
Media:
Even though this crocodilian is super cool in design and function, there has not been appearances of this crocodilian in any sorts of media which is a bit disappointing and I hope we can get to learn more about this crocodilian.
Merchandise:
I looked around for merch and there was not any merch related for Arizonasaurus. I am thinking of maybe doing a sticker or something for Triassic reptiles. What do you think? Let me know in the comments below.
If you want to see these dinosaurs or even crocodilians like this post illustrated for your own, be sure to click the button below as I have started my new Fiverr commission channel and it would be a great way to support my blogging endeavor as I try my best to bring more dinosaur and many more creature related content to you guys!!! See you again soon!
