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Reposted by Armin Reindl

_crocodiles @crocodiles.bsky.social · 23h

At the end you’ll notice this Cuban croc (C. rombifer) blink their third eyelid aka nictitating membrane. This helps protect their eyes underwater, while still allowing them to see.

#Croctober #cubancrocodile 🐊

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Armin Reindl @arminreindl.bsky.social · 19h

A very interesting developement as of late is that we're finally starting to see more basal forms from this group be described, so here's hoping we'll also find some transitional forms of the derived clades

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Armin Reindl @arminreindl.bsky.social · 19h

and the final animal in this little selection is Benggwigwishingasuchus, likely a coastal animal that lived at the same time as the enormous ichthyosaur Cymbospondylus

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Armin Reindl @arminreindl.bsky.social · 19h

The sail-backed ctenosauriscids are among the oldest members of this group yet also the strangest, Lotosaurus was a heavily built herbivore known from almost 40 specimens, Effigia is a member of the Shuvosauridae, which almost appear like an early attempt at ornithomimids

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Armin Reindl @arminreindl.bsky.social · 19h

I told you I'd get to poposauroids
Day 14 of #Croctober and lets just take a moment to appreciate the absolute insanity that are derived poposauroids.
Throughout the Triassic this group brought forth forms with sailed backs, proto-theropods and more
All art by Joschua Knüppe

An illustration of Arizonasaurus by Joschua Knüppe. The animal somewhat resembles Spinosaurus or Dimetrodon, with a large rounded sail on its back. The neck is relatively short, the head long and triangular. It's shown with a bipedal posture and short front limbs that dangle from the body.

An illustration of Lotosaurus by Joschua Knüppe. It has a stocky adn robust body, short neck and a robust beaked head. It is shown wallowing in the mud.

An illustration of Effigia by Joschua Knüppe. The animal appears similar to a featherless ornithomimosaur with longer hindlimbs, short front limbs, a long neck and a beaked snout. It is shown standing next to a nest made of folliage by a river, rearing up while a phytosaur is holding an egg in its mouth.

An illustration of Benggwigwishingasuchus by Joschua Knüppe. The animal has relatively long legs, an elongated neck and a narrow, pointed snout. It is depicted standing atop the skull of a massive ichthyosaur, the skull alone longer than the entire Benggwigwishingasuchus.

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Armin Reindl @arminreindl.bsky.social · 1d

especially given that the material was found shortly after Tanzania became independent of Britain
Anyways relevant paper here:
doi.org/10.1098/rsos...

A new pseudosuchian archosaur, Mambawakale ruhuhu gen. et sp. nov., from the Middle Triassic Manda Beds of Tanzania | Royal Society Open Science

The Manda Beds of southwest Tanzania have yielded key insights into the early evolutionary radiation of archosaurian reptiles. Many key archosaur specimens were collected from the Manda Beds in the 19...

doi.org

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Armin Reindl @arminreindl.bsky.social · 1d

but given it was never formally published it was given the name Mambawakale, literally "ancient crocodile" in Kiswahili. It's perhaps a little on the nose, but it has a great ring to it and certainly an improvement over just being named after a British guy

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Armin Reindl @arminreindl.bsky.social · 1d

More on poposauroids later
Anyways, the bones of Mambawakale were found back in the 60s, but like several other finds of that expedition weren't formally described until half a century later. Alan Charig initially intended the name Pallisteria after a friend of his...

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Armin Reindl @arminreindl.bsky.social · 1d

For Day 13 of #Croctober I just wanna give a quick shout out to Mambawakale from the Mid Triassic Manda Beds of Tanzania. It was originally placed in a polytomy at the base of Paracrocodylomorpha, but was recently recovered as an early poposauroid
Illustration by Gabriel Ugueto

An illustration of Mambawakale scaled to a silhouette of Steve Irwin. The animal is about as long as a large modern crocodile, but with noticably less armor, a deeper torso, a rectangular skull and much longer legs, resembling a generalized "rauisuchian"

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Armin Reindl @arminreindl.bsky.social · 2d

Both relevant papers:
doi.org/10.1643/0045...
doi.org/10.1098/rsos...

A New Miniature Horned Crocodile from the Quaternary of Aldabra Atoll, Western Indian Ocean

A new crocodylid is described on the basis of fragmentary, but diagnostic, material from the Quaternary of Aldabra Atoll. It differs from all other known crocodylians, living or extinct, in having a p...

https://doi.org/10.1643/0045-8511(2006)6[149:ANMHCF]2.0.CO;2

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Armin Reindl @arminreindl.bsky.social · 2d

Artwork above by Manusuchus
Late Pleistocene fossils of giant tortoises from the Seychelles also bear the bite marks of crocodilians, suggesting that Aldabrachampsus, or another crocodilian, either killed or scavenged them, giving us this brilliant figure from Scheyer et al 2018

An illustration from Scheyer et al 2018 showing two scenarios on how crocodilian bite marks may have ended up on the shells of a giant tortoise. The top illustration shows the animal submerged underwater, slowly approaching a drinking tortoise. The illustration below shows the crocodilian coming out of the water to feed on the corpse of an already dead tortoise, surrounded by flies and a coconut crab.

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Armin Reindl @arminreindl.bsky.social · 2d

#Croctober Day 12
Probably among the most obscure recently extinct crocodilians is Aldabrachampsus, a small (up to 2.5 meter) long animal of uncertain placement with a pair of rounded squamosal horns that lived on the Seychelles around 100.000 years ago

An illustratoin of Aldabrachampsus by paleoartist Manusuchus. The illustration shows the animal as similar to modern dwarf crocodiles with a short, blunt snout, interlocking teeth, large bulging eyes but different in having large, rounded horns above the ears.

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Armin Reindl @arminreindl.bsky.social · 3d

And the paper doi.org/10.1016/j.gr...

Redirecting

doi.org

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Armin Reindl @arminreindl.bsky.social · 3d

For #Croctober Day 11 we got Confractosuchus (art by Julius Csotonyi)
Confracto once inhabited the Winton Formation of Australia, but unlike the tiny Isisfordia was sizable enough to even feed on dinosaurs. Which we know because we found the bones of an elasmarian in its stomach

$Paleoart and a 3D scan of Confractosuchus. On top the animal (drawn by Julius Csotonyi) is shown lunging out of the water in a wooded region, a small elasmarian ornithopod in the process of being swallowed. The graphic below it shows a 3D scan of the fossil material, the skull largely resembles modern crocodiles.$

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Armin Reindl @arminreindl.bsky.social · 4d

Our fun fact for #Croctober day 10
Crocs even developed beaks at some point. Macelognathus (art by Scott Reid) is an early crocodylomorph from the Morrison Formation who's lower jaw tip was flattened and beak like with teeth further back in the jaw.

An illustration of the lower jaw of Macelognathus. The tip of the snout is expanded and flattened, somewhat resembling a wider duck bill. Behind the beak section multipole toothsockets are visible.

Paleoart of Macelognathus by Scott Reid. The animal has a long tail and incredibly lanky legs, almost resembling a windhound more than a crocodile. The skull is narrow and triangular with rows of teeth and a beaked tip.

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Armin Reindl @arminreindl.bsky.social · 5d

Aetosaurs are an interesting group that I want to dig deeper into at some point (if I find the time), but rest assured the osteoderms are incredibly distinct in these guys
This does mean that frustratingly theres a bunch of species just named from a handful of armor plates tho

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Armin Reindl @arminreindl.bsky.social · 5d

It's shown quite nicely in this illustration of Gorgetosuchus by Matt Celeskey

An illustration of Gorgetosuchus by Matt Celeskey. The animal is shown in 3/4 view from behind. It is heavily armored with a triangular snout and a broadened nose tip. A close up shows the overall appearance of a ring of osteoderms, with notes describing its anatomical details.

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Armin Reindl @arminreindl.bsky.social · 5d

While the osteoderms are isolated, we can see the anterior bar in the bones of Rioarribasuchus, therefore we can tell whats the front and whats the back of each osteoderm and therefore see that the spikes curve forward

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Armin Reindl @arminreindl.bsky.social · 5d

Great question, the reason we know is due to how the armor of aetosaurs interlocks. Generally speaking, aetosaur osteoderms overlap the ones behind them, and the region that is overlapped is known as the anterior bar (its really obvious in some species).

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Armin Reindl @arminreindl.bsky.social · 5d

Really its an entire saga I do recommend reading up on, thankfully a lot of the procedure has been thoroughly documented by Mike Taylor and Darren Naish around the time of the events in 2007/2008

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Armin Reindl @arminreindl.bsky.social · 5d

Of course the case of Rioarribasuchus/Heliocanthus was not the only thing to cause Aetogate, another notable case is what was the New Mexico team seemingly plagiarizing or at least taking credit for the findings of Jeff Martz (illustrator of the first image) and other such cases

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Armin Reindl @arminreindl.bsky.social · 5d

changing their mind, publishing an incredibly brief (not even 2 full pages) report coining the name Rioarribasuchus before Parker was able to publish his own study, which would have named the animal Heliocanthus

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Armin Reindl @arminreindl.bsky.social · 5d

a sentiment that William G. Parker did not share, instead suggesting that the animal was its own distinct taxon that was yet to be given a name (something Parker was working on).
The New Mexico team continued to refer it to Desmatosuchus, that is until suddenly...

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Armin Reindl @arminreindl.bsky.social · 5d

So Aetogate is a controversy that took place in the late 2000s when several researchers of the New Mexico Museum of Natural History were accused of plagiarism. In the case of Rioarribasuchus for instance the animal was long considered a species of Desmatosuchus...

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Armin Reindl @arminreindl.bsky.social · 5d

Day 9 of #Croctober, featuring Rioarribasuchus
Outwardly a fascinating and imo quite underappreciated animal given the strange, forward-pointing spines on the tail scutes
But while it looks unique, Rioarribasuchus is better known for being central to the Aetogate controversy

An illustration of "Rioarribasuchus" by Jeff Martz. It is shown as a robust animal with extensive armor plating and a small triangular head. The front limbs are shorter than the hindlimbs and the tail features a ridge of forward pointing spines throughout most of of its length.

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