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Diversity of the Crurotarsi by Eurwentala Diversity of the Crurotarsi by Eurwentala
Some examples of the diversity of the crocodile-line archosaurs or Crurotarsi. This group was very common and diverse in the Triassic, and only a bit less so in the Jurassic and Cretaceous. Many of them were highly specialized and seem to have been active, possibly even warm-blooded animals. The group has many interesting examples of convergent evolution with dinosaurs and other groups. Now only the modern crocodiles remain.

In this picture, from top to bottom:
Saltwater Crocodile, Crocodylus porosus. The largest modern species of crocodile. An opportunistic predator that can eat anything from water buffalo to sharks.
Yacarerari. Belongs to the Cretaceous group Notosuchia. It was a cat-sized animal with very unusual mammal-like teeth.
Metriorhynchus. Member of the completely aquatic group Thalattosuchia. It had a tail fin and it's limbs were modified into flippers. It might have been viviparous, since it's body plan sure doesn't look suitable for laying eggs on dry land. Thalattosuchians are strongly convergent with ichthyosaurs and dolphins.
Terrestrisuchus. A small, obviously cursorian Sphenosuchian that could have weighed around 15 kg. It might be a juvenile specimen of Saltoposuchus.
Postosuchus. A member of Rauisuchia. It might have been partly or completely bipedal, since it's front limbs are small and weak. It was a large predator that had very similar head and teeth as the tyrannosaurid dinosaurs.
Effigia. Another dinosaur-like rauisuchian. It was a fast-running, bipedal animal very similar to ornithomimosaurs (the ostrich-mimic dinosaurs). It even had a toothless beak.
Desmatosuchus. A triassic aetosaur with very impressive armour. It was a herbivore with a surprisingly pig-like head.
Rutiodon. A crocodile-like phytosaur. Despite their appearance, phytosaurs were not closely related to the modern crocodiles. They seem to be another example of convergent evolution.
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:icongrisador:
grisador Featured By Owner Aug 19, 2015
Crocodylmorpha is The best & most successfull group of animals.
They even rivaling The sharks & cockroach'es at evolution, survival and Life
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:iconhublerdon:
HUBLERDON Featured By Owner Jul 21, 2015  New Deviant Hobbyist General Artist
No prisitichampsus?
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:iconwhatpipeswhy:
whatpipeswhy Featured By Owner May 18, 2015
Crurotarsi are fascinating. It's a shame the stem-crocodile branch of the Archosaur family tree is so obscure in pop culture, compared to the stem-bird lineage - imagine how much little kids would love to play with toy versions of these creatures! Or the way crurotarsan forms could be added into the potpourri of fantasy dragon designs.
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:iconacepredator:
acepredator Featured By Owner May 5, 2015
And add the stomatosuchines......
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:iconfejesvalentin:
FejesValentin Featured By Owner Apr 29, 2015  Hobbyist General Artist
How about Simosuchus?
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:iconhelixdude:
Helixdude Featured By Owner Jan 6, 2015  Hobbyist Traditional Artist
I remember watching "Walking with Dinosaurs(The original series, not that abomination with the Pachyrhinosaurus) and how they portrayed Postosuchus as completely quadrupedal, good thing science marches on as i prefer it being at least partially bipedal. 
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:iconeurwentala:
Eurwentala Featured By Owner Jan 8, 2015
I still haven't quite figured out how they make sense as bipeds, but apparently they have to. :)
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:iconjdailey1991:
Jdailey1991 Featured By Owner Feb 25, 2015
I don't get where they got the idea of someone as heavy as Postosuchus to be bipedal in the first place.
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:iconeurwentala:
Eurwentala Featured By Owner Feb 27, 2015
Well, things like Tyrannosaurus or Allosaurus are quite a bit heavier and obviously bipedal. It's not the size, but the proportions that make it look odd and unlikely. But if you take an actual look at the forelimbs, they are ridiculously tiny and slender, and fairly easily give the idea of a biped (see the discussion here: phenomena.nationalgeographic.c… ).

Postosuchus doesn't really make much sense on any number of legs, but personally I'd favour the facultative biped hypothesis. On all fours when standing or moving slowly, on hind legs when running, or something like that.

Besides, it wouldn't be the only oddly unbalanced biped. Have you seen videos of pangolins walking? www.youtube.com/watch?v=gz4HXy… They're not exactly small animals either, with the giant pangolin weighing at least 33 kg.
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:iconthe-episiarch:
The-Episiarch Featured By Owner Dec 6, 2014
Nice! The Crurotarsi certainly get overlooked by most and end up in the shadow of the dinosaurs (even though they are very interesting in their own right). Ironically enough, some of those bipedal rauisuchians rather resemble the scaly theropods many people (who haven't come to terms with feathered dinosaurs) still think of when they think "dinosaurs". My fondness for these reptiles can be seen this piece here the-episiarch.deviantart.com/a…
Which features a few of the genera you have illustrated above (though my piece is a rather off-beat take on those reptiles).
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:iconheytomemeimhome:
Heytomemeimhome Featured By Owner Apr 10, 2014
Ah if only anatosuchus and other notosuchians were here
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:iconeurwentala:
Eurwentala Featured By Owner Apr 13, 2014
Yeah, I should make an updated version about this. :)
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:iconfancykarp:
FancyKarp Featured By Owner Jan 20, 2014  Hobbyist Digital Artist
Yacarerani, I feel so proud about one of the national languages of my country gave a name to a prehistoric creature! :D
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:iconhellraptor:
Hellraptor Featured By Owner Sep 18, 2013  Hobbyist Digital Artist
Hard to belive that some of them are classed as crocodiles even though they didnt look like that. Very nice comparison pictue.
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:iconaloodonguy67:
Aloodonguy67 Featured By Owner Jun 12, 2013  Student Artist
I love it!
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:iconnixkat:
NixKat Featured By Owner Mar 4, 2013  Hobbyist Traditional Artist
Cool.
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:iconeurwentala:
Eurwentala Featured By Owner Mar 8, 2013
Thanks. :)
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:iconmechatherium:
Mechatherium Featured By Owner Feb 17, 2012  Student Digital Artist
As for Metriorhynchus being viviparous, if hard evidence of that was found it would be fascinating. That would make it the only archosaur I know of that ever was.
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:iconeurwentala:
Eurwentala Featured By Owner Feb 24, 2012
Yes, it would be really fascinating, though unlikely. I'd think that if viviparity was easy to evolve in archosaurs, it would have happened at least a few times, if not more than a hundred, as it has in squamates.
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:iconpristichampsus:
Pristichampsus Featured By Owner Oct 28, 2012  Professional General Artist
Thallatosuchian hindlegs are larger, but not huge, I imagine if a turtle can haul out and dig like that, surely a dako or geo could.
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:iconeurwentala:
Eurwentala Featured By Owner Oct 31, 2012
True, but turtles are much smaller than the largest thalattosuchians: the biggest recorded leatherback turtles have been slightly more than 3 meters from head to tail. Plesiosuchus could reach 7. That would put it in the same size class with female orcas or pygmy right whales.

If they really could haul theirselves on dry land to lay eggs and get back to the ocean, they had to be indcredibly strong. And I don't think they could actually dig a nest to put the eggs into. The alternative, viviparity, doesn't seem likely either, but they had to breed somehow, right? :)
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:iconpristichampsus:
Pristichampsus Featured By Owner Oct 31, 2012  Professional General Artist
Pig-nosed turtle eggs are stimulated to hatch by the nest being flooded, so maybe thalattosuchians were partly ovoviparous, the young and eggs developed inside, and at hatching time, were ejected, the young would then react to the water and hatch...
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:iconill-fated-jedi:
Ill-Fated-Jedi Featured By Owner Oct 22, 2011
Great work. I wish you had included Stomatosuchus and Quinkana for a bit more crocodilian diversity, but I love your Notosuchid. Also I've heard rumours that we can't call them all Crurotarsi anymore because of the deviant nature of phytosaurs. [link]
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:iconeurwentala:
Eurwentala Featured By Owner Oct 23, 2011
I read it too. It's a shame. Crurotarsi is a lot better name than Pseudosuchia. And Pseudosuchia doesn't make any sense anyway.

Maybe someone could just redefine Crurotarsi as anything that's closer to crocodiles than birds. Though I don't know enough about taxonomy to sya if it's possible.

These were drawn for a family tree published with an article about modern crocodile physiology, and so couldn't include all the cool cruro... umm, pseudosuchians, but I might do a larger family picture later. Stomatosuchus is especially interesting, and there are plenty of freaky notosuchids and baurusuchids too. And the sail-backed guys are missing also.
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:iconill-fated-jedi:
Ill-Fated-Jedi Featured By Owner Oct 23, 2011
Sadly I think the problem is that Phytosaurs have been found to be outside the archosaur branch, but being more of a bird person I'm not entirely certain of the technical issues to resolve.

It would be awesome if you could expand to include some of the wierder Cenozoic and later Mesozoic crocs, because apart from Arizonasaurus these are most of my favourites from the Triassic era and of course the salty for comparison.

Cheers
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:iconeurwentala:
Eurwentala Featured By Owner Oct 23, 2011
Yes, and since the original definition or Crurotarsi is based on phytosaurs, Crurotarsi now techically includes everything that branches after phytosaurs, including dinosaurs and pterosaurs, and that's not exactly useful.

If Crurotarsi was defined again to include everything closer to crocodiles than birds, it would include the branch of the tree everybody wants it to include. Much like theropods are defined as everything closer to Allosaurus than Saltasaurus.

Taxonomy has a complex set of rules, though, and I'm not at all sure if names can be simply redefined like this.
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:iconill-fated-jedi:
Ill-Fated-Jedi Featured By Owner Oct 23, 2011
I think the latter sentiment will win out, in the end, and we will have to content ourselves to the akward-sounding Pseudosuchia. Alternatively, a new name could be proposed for the group. However, there are exceptions, as taxonomists still prefer to call Megapnosaurus Synatarsus because Synatarsus is more serious even though it shares its latin name with a beetle species.
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:iconthemorlock:
TheMorlock Featured By Owner Sep 23, 2011  Student General Artist
Effigia is one strange creature.
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:iconeurwentala:
Eurwentala Featured By Owner Sep 24, 2011
It sure is. No wonder it was first described as an ornithomimid dinosaur, even though it lived tens of millions of years before them.
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:icondotb18:
DOTB18 Featured By Owner Sep 15, 2011
Personally, I'm enclined to think that metriorhynchids were ovoviviparous for the simple fact that, so far, there hasn't been a documented example of vivipary in any known archosaurs, extinct or otherwise. So until someone finds a fossil of a Metriorhynchus that died while it was pregnant or in labour, I'm going to envision them writhing up beaches and laying thier eggs in the sand like sea turtles.
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:iconeurwentala:
Eurwentala Featured By Owner Sep 16, 2011
Given the apparent ease and frequency of evolution of viviparity in squamates, you may well be right. It's just a bit difficult to imagine a five-meter long legless crocodile crawling on land to lay eggs. On the other hand, it's not that much bigger than a large specimen of leatherback turtle...
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:icondotb18:
DOTB18 Featured By Owner Sep 16, 2011
Also, I've noticed that metriorhynchids have more well developed leg bones than most marine reptiles, like ichthyosaurs or mosasaurs. In the latter two, the majority of the flipper is mostly made up of the foot. But in metriorhynchids, the femur makes up about half the length of the hind flippers. Now that I think about, I think they may have moved somewhat like sea turtles when on land, but somewhat in reverse; sea turtles mostly push with thier front flippers, while metriorhynchids would have pushed with thier hind flippers, either in an alternating "walk" or a simultanious "hop". I'm just guessing at this point, it's just that no one seems to have taken metriorhynchid reproduction into any sort of serious consideration.
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:iconeurwentala:
Eurwentala Featured By Owner Sep 17, 2011
I was imagining a huge metriorhynchid "hopping" with it's back flippers over a beach. Poor thing. :) But it just might make a funny drawing...

Oh well, I'm full of ideas since I have no time to draw for weeks.
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:icondotb18:
DOTB18 Featured By Owner Dec 9, 2011
It seems that I've been mistaken. [link]
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:iconeurwentala:
Eurwentala Featured By Owner Dec 9, 2011
Oh, that's interesting. Though Hyphalosaurus is a choristodere, not an archosaur proper. The phylogenetic position of choristoderes is apparently not very clear, they could be basal members of the lepidosaur side of the tree as well as basal archosauromorphs.
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:iconswampqueen:
Swampqueen Featured By Owner Jun 7, 2011
Holy cow! One of them had a toothless beak? I never knew the crocodilians were so amazing in their variety of forms.
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:iconmasonday:
masonday Featured By Owner May 11, 2011
That was so awesome!
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:iconzippo4k:
Zippo4k Featured By Owner Dec 13, 2010
What were their relationship to the dinosaurs?
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:iconeurwentala:
Eurwentala Featured By Owner Dec 14, 2010
They are both archosaurs, and thus more closely related to each other than, for example, they are to lizards. Their common ancestors, or the early archosauromorphs, appeared in the Late Permian and Early Triassic. Somewhere around this time a split happened in the archosaur family tree. The other half is called the crocodile lineage or Crurotarsi (also sometimes called Pseudosuchia). And the other is the bird lineage (Ornithodira or Ornithosuchia) that includes birds, other dinosaurs and probably pterosaurs. So, while they are quite closely related and even pretty similar to dinosaurs, they are clearly separate branches.
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:iconzippo4k:
Zippo4k Featured By Owner Dec 14, 2010
Thanks for answering back! That's rather interesting... SO then they're just sister groups... Cool!
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:icondemiantort:
demiantORT Featured By Owner Apr 13, 2010
I like to see differen species in one pic, and there are some I don't frequently see, but why do they have to have cute eyes?
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:iconeurwentala:
Eurwentala Featured By Owner Apr 20, 2010
Now that you mention it, I don't know. I just like to make animals look likeable, because that's what they look like to me.
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:icondemiantort:
demiantORT Featured By Owner Apr 21, 2010
XD I don't see corocodiles very much likeablem but if that is your interpretation its ok for me.....Hauskaa päivän jatkoa ^^ (I want to lear suomi, because of Ruoska)
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:iconeurwentala:
Eurwentala Featured By Owner Apr 21, 2010
There aren't many cuter things in the world than a baby crocodile. :)

Kiitos ja hauskaa päivän jatkoa!
(And congratulations for choosing a quite weird and very difficult language)
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:iconred-tatsu:
Red-Tatsu Featured By Owner Apr 13, 2010
These pictures are wonderful! I especially like Effigia.
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:iconslugozaur:
Slugozaur Featured By Owner Apr 12, 2010  Hobbyist General Artist
great idea and even better realization !
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:iconbabbletrish:
babbletrish Featured By Owner Apr 12, 2010  Professional Traditional Artist
Very nice, sensitive portraits of these underappreciated animals.
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:iconel-moppo:
El-Moppo Featured By Owner Apr 8, 2010   Digital Artist
Amazing.
I Loves It! :D <3 :)
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:icongothcakes:
Gothcakes Featured By Owner Apr 3, 2010
I love the way these are drawn, the eye's somehow makes them look almost friendly...
but anywho I love your work ^^
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:iconmakutu:
makutu Featured By Owner Apr 1, 2010
really interesting, the colours are superb.
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