The Prehistoric Croc Thread- Anything crocodilian related

Adam Khor

Pebas was the megawetland (sometimes called a lake, sometimes called a freshwater/brackish sea) that covered what is today the Amazon basin during the Miocene.

https://phys.org/news/2019-02-giant-animals-amazonian-mega-wetland.html



It was the home of the notorious giant caiman Purussaurus, one of the largest crocodilians ever:

Adam Khor

Phytosaurs were superficially crocodile-like reptiles and occupied a similar niche during the Triassic. Most of the known species were freshwater-based but like crocodiles, it seems they did venture to sea- this new species being an example.

https://www.livescience.com/65460-ancient-crocodile-like-animal-discovered.html

Researchers excavated the remains of four of these now-extinct sea monsters from the rocky slopes of the Austrian Alps. But even at 13 feet long (4 meters), these creatures — known as phytosaurs — weren't fully grown.
The phytosaurs were only about 8 years old when they died, and they were "still actively growing," according to a bone analysis

It should be noted that the largest phytosaurs, such as Rutiodon, Redondasaurus and Smilosuchus, could be as long as 8-12 m, making them comparable to the largest crocodilians and among the largest predatory reptiles of prehistory.

Adam Khor

It is but a tooth, but is interesting because until now, no juvenile Deinosuchus fossils had been described. The tooth came from an individual maybe less than one meter long.

https://bioone.org/journals/Bulletin-of-the-Peabody-Museum-of-Natural-History/volume-60/issue-1/014.060.0104/First-Record-of-a-Small-Juvenile-Giant-Crocodyliform-and-its/10.3374/014.060.0104.short

Deinosuchus (formerly known as Phobosuchus) was one of the largest most formidable crocodilians known from the fossil record; it lived during the late Cretaceous in coastal waters of North America (specifically, the coasts of the shallow sea that split the subcontinent in two), and apparently could travel long distances by sea, as do some crocodiles today.
Despite its crocodile-like appearance and tolerance for salinity, it was more related to caiman and alligators than to crocodiles proper.

There's actual, solid evidence in the form of bite marks that Deinosuchus fed on large dinosaurs, among other things.

Adam Khor

https://phys.org/news/2019-06-ancient-croc-preyed-dinosaurs.html

Adam Khor

http://www.sci-news.com/paleontology/extinct-crocodyliforms-vegetarians-07336.html

Adam Khor

Tiny Cretaceous croc named "ankle-biter"

https://www.sacurrent.com/the-daily/archives/2019/07/03/new-species-of-ancient-ankle-biting-reptile-named-by-witte-museum-paleontologist

Insect Overlord

I can't add anything to this discussion, but I just wanted to comment that your thread title is wonderful.

Fathom

Why prehistoric larger than today?

Adam Khor

Fathom wrote: »

Why prehistoric larger than today?

The more I think about this, the more difficult I find it to answer.

It is not as easy as saying they started out big and shrank over time; in fact, the fossil record does not support this at all. The first crocodilians (I'm using crocodilian in the broad sense here) were small, and even when, eventually, you start getting giant forms (starting in the Jurassic period), the smaller forms are still more abundant and more diverse. This does not change at any moment in their history; gigantic crocs were the exception, not the rule.

Of course if you separate crocodilians into two categories, one being modern ones and the other extinct ones, you'll find more giants in the latter, but only because it spans millions and millions of years. Some giant crocodilians did coexist, but not all; most are separated from one another by millions of years.

That being said, it is true that some of the extinct giants grew considerably larger than today's crocodiles. IIRC the largest reliably measured saltwater crocodile (Crocodylus porosus, usually considered the largest reptile in the world), was Lolong, who died in 2013 in captivity and was 6.17 m, and weighed over 1000 kg. There is some skeletal and anecdotal evidence of larger saltwater crocodiles in the wild; the very largest may plausibly grow to around 7 m.

Compare this to some of the largest prehistoric crocodilians, such as Deinosuchus, Sarcosuchus, Purussaurus, Rhamphosuchus or Machimosaurus, which are estimated at 9-10 m (maybe 12 m for the very largest). Some of these giants have been estimated at 3, 5, even 10 tons. But they represent only a tiny fraction of the total of extinct crocodilian genera/species, which are often within the range of our living ones or smaller.

Now there's something interesting I've noticed, which is that many of the prehistoric giants lived in conditions different from those of modern day crocodiles. For example, many of the giants were partially or fully marine (Deinosuchus, Machimosaurus, Piscogavialis, Toyotamaphimeia). Large size allows a marine animal to travel longer distances across the sea, with extra protection against other predators (sharks, etc) and the ability to spend long periods without feeding; insane weight is not an issue if you spend most of your life at sea.
Many kinds of marine reptiles (ichthyosaurs, mosasaurs, plesiosaurs) tended towards gigantism. Even the saltwater crocodile, the largest of our days, is the one most likely to venture out to sea, and to travel long distances between islands, etc, although it can´t be considered a truly marine animal.

As for the prehistoric giants known to have lived in freshwater, they are often associated with huge river or lake systems that do not exist today. For example, Sarcosuchus and Stomatosuchus lived in a huge delta where the Sahara desert is now. Purussaurus, Gryposuchus and Mourasuchus lived in what is today the Amazon basin but back then was a gigantic wetland or inland sea, at times connected to the ocean, and rich in huge aquatic prey. You only get these super giant crocodilians for as long as these huge water bodies exist- when they dry out or become reduced, the giant crocs dissappear.

May as well mention that at least in the case of Sarcosuchus, there's been suggestion that it grew to a much faster pace than modern day crocodilians, possibly as a strategy to reduce its vulnerability to other predators (remember there were dinosaurs and other crocodile-like reptiles around), and so they reached larger sizes earlier than modern crocs, and kept growing afterwards for many, many years. Without humans to shoot them on sight, the big ones would've been practically safe from predation and may have lived for over a hundred years unmolested, unlike what happens with crocodiles today.

Capt'n Midnight

Fathom wrote: »

These organisms evolved? Did not suffer extinction as many species of dinosaurs?

Two land crocs , Quinkana and Pallimnarchus may have survived until humans arrived in Australia.

Pallimnarchus was the size of a salty :eek:

Adam Khor

Capt'n Midnight wrote: »

Two land crocs , Quinkana and Pallimnarchus may have survived until humans arrived in Australia.

Pallimnarchus was the size of a salty :eek:

One of the Quinkana species was about that size too. I think there's even a cave painting somewhere in Australia depicting it.

Capt'n Midnight

Fathom wrote: »

Why prehistoric larger than today?

Koolasuchus was a half ton amphibian with a similar lifestyle to crocs. Lived down in Antarctica back in the day.


https://i.redd.it/vtfawq79c7111.jpg

Adam Khor

Capt'n Midnight wrote: »

Koolasuchus was a half ton amphibian with a similar lifestyle to crocs. Lived down in Antarctica back in the day.


https://i.redd.it/vtfawq79c7111.jpg

It would appear that it took advantage of the low temperatures that prevented crocodilians from colonizing those antarctic river systems. As soon as the temperatures rise and crocodilian fossils start appearing in those regions, Koolasuchus vanishes.

The closest thing we have to it today are the giant salamanders (Andrias) found in China and Japan. Also ambush predators, but at 1.5-1.8 m, nowhere near as large as their long extinct cousin.

Fathom

Adam Khor wrote: »

This does not change at any moment in their history; gigantic crocs were the exception, not the rule.

Thanks for clarification Adam.

Capt'n Midnight wrote: »

Two land crocs , Quinkana and Pallimnarchus may have survived until humans arrived in Australia.

Food chain competition?

Capt'n Midnight

Fathom wrote: »

Food chain competition?

Sharks in the estuaries and rivers,
Salties and fresh water crocs.
And the giant lizard megalania running about the place too
And a 10m snake, the Bluff Downs giant python ambushing at water holes.

With some overlap in niches.

Adam Khor

Reading up on Pallimnarchus and it seems like it may have been even bigger than salties.

This is from a 2012 article reporting on a possible Pallimnarchus find:

University of New South Wales palaeontologists who found the fragment of crocodile jaw state that this individual was at least eight metres long and there may have been others of its kind that were even larger, perhaps reaching the size of Sarcosuchus, a twelve metre long Crocodylian that lived during the Late Cretaceous geological period and preyed on dinosaurs.

(Note that they make a mistake here, as Sarcosuchus lived in the early Cretaceous, not late Cretaceous)

The fossil was discovered by undergraduate Bok Khoo from the University of New South Wales on July 10th, it is part of the lower jaw (dentary). The fossil bearing strata consists of several layers which represent ancient river deposits. The dig site is close to the current course of the Liechardt River and the sediment is disturbed when the water levels rise and this helps to expose new fossil finds. The river may help reveal fossil material but being close to the river does have its drawbacks. The location is known for its Saltwater and Freshwater crocodiles as well as sharks and sting rays. The field team have to be wary of attacks from extant crocodiles as they search for the fossilised remains of extinct ones.

Gilbert Price, a palaeontologist with Queensland University has commented that the jaw bone represents a substantial individual, one crocodile that was very probably an apex predator in the region. The fossil has yet to be accurately dated, it belongs to either the Pleistocene or the earlier Pliocene Epoch. The Pliocene ended approximately 1.6 million years ago, the Pleistocene Epoch followed and lasted until approximately 10,000 years ago. The fossil is eroded, a result of the river action and the teeth have been lost but the tooth sockets which measure up to four centimetres in diameter indicate that this predator had very large, conical-shaped teeth.

Professor Mike Archer of the University of New South Wales described the fossil as “weird” and he could not rule out that this fossil find could represent a new species.

The bite marks of the largest known species, Pallimnarchus pollens, have been found on the bones of the giant marsupial Diprotodon, which grew as large as a modern rhinoceros and would've been the largest available prey:

Adam Khor

https://palaeo-electronica.org/content/2019/2602-mourasuchus-amazonensis





Mourasuchus was a contemporary of the better known Purussaurus, and like it, a member of the caimanine group of the Alligatoridae family. It was also a giant, growing to maybe around 10, possibly up to 12 m long, but its small teeth and skull structure would suggest it was specialized in much smaller prey, maybe even by filter-feeding, fullfilling a role similar to that of the filter-feeding Stomatosuchus of the Cretaceous.

This would've allowed it to coexist with the equally large Purussaurus and Gryposuchus without competing for food with them.

Adam Khor

These little land crocodiles of the Cretaceous may have had a greater ability to vocalize than modern day kinds.

https://www.sciencedirect.com/science/article/pii/S0195667118304051?via%3Dihub

Adam Khor

Mystery of Mystriosaurus:

https://www.sachspal.de/mystriosaurus/

Adam Khor

The so called "Crocodylus bugtiensis", a giant crocodilian found in Oliocene Pakistan fossil sites, has been renamed as Astorgosuchus bugtiensis, as it was found to be more distantly related to modern crocodiles than thought, and possibly closer to Asiatosuchus.

This creature would've been around 7-8 m long, with very robust jaws and teeth. Its bite marks have been found on the bones of Paraceratherium/Indricotherium, formerly considered the largest land mammal of all times.

https://www.tandfonline.com/doi/abs/10.1080/02724634.2019.1671427?journalCode=ujvp20

Capt'n Midnight

Adam Khor wrote: »

This creature would've been around 7-8 m long, with very robust jaws and teeth.

we've all seen a saltie yada, yada, yada , whatever

Its bite marks have been found on the bones of Paraceratherium/Indricotherium

It had a 30 tonne rhino on the menu :eek: :eek: :eek: :eek: :eek:

Adam Khor

Giant caiman Purussaurus mirandai had special adaptations to better support its weight on land; it would've been able to walk and move about like modern crocodilians despite weighing maybe up to 3 tons (Purussaurus brasiliensis was even bigger).

https://www.bbc.com/news/world-latin-america-50827002

Adam Khor

Brazil's first ornithosuchid, Dynamosuchus. It would've been over 2 m long and is suggested to have been a scavenger (why not an opportunist like most meat eaters though?)

https://api.nationalgeographic.com/distribution/public/amp/science/2020/02/rare-fossil-bone-crushing-crocodile-cousin-found-brazil

Adam Khor

Giant teleosaurid remains found in Colombia.

https://mostlymammoths.wordpress.com/2020/03/01/enormous-crocodylomorph-discovered-in-colombia-dirley-cortes/



Teleosaurids were a group of crocodylomorphs that roamed the oceans during the Jurassic and early Cretaceous. They include the largest known sea crocodile of all times (and largest crocodile of the Jurassic), Machimosaurus, which is believed to have reached 9-11 m long and was apparently quite widespread and long-lived as a genus. Bite marks of Machimosaurus have been found on the fossilized bones of sauropod dinosaurs from the Jurassic, but its long, slender jaws would suggest aquatic prey was the basis of its diet.

The Colombian remains may belong to a Machimosaurus.

Preserved for approximately 120 million years in a calcareous concretion, it was discovered in Villa de Leyva by Carlos Gonzalez. It is a partial fossil, albeit very well preserved. The state of the armoured plates (known as “osteoderms”), dorsal ribs, dorsal centra and metapodial elements indicate rapid burial shortly after death. The species of this fossil is unknown as neither teeth nor cranial elements were found. Several ammonites found in association with this fossil indicate its age, and the surrounding sediment suggests that when this crocodylomorph met its end, the area may have been a “a salt tidal flat depositional environment.”

Studying the microscopic structure of the bone (“osteohistology”) provided fascinating insight into the life of this creature. The size of the bones discovered, as well as the density of blood vessels within those bones, indicates that this reptile was an enormous creature. But even the 9.6-meter estimate is conservative, because larger vertebrae for this specific animal may have existed, but they were not preserved in the concretion.

Further osteohistological research revealed lines within the osteoderms. Much like the rings of a tree, the rings in a proboscidean tusk or information contained with fossil teeth, paleontologists can read these lines to infer whether this reptile experienced times of famine and hardship, as well as how seasons may have affected its level of activity or overall health.

Unfused neurocentral sutures suggested the fossil was an adult, but not one that was fully mature at the time of its death.

Adam Khor

Fossil of small pholidosaur Crocodilaemus robustus found in France. The creature was not even a year old at the moment of death and measured around 56 cm. It would've lived at about the same time as Archaeopteryx and Compsognathus, in a shallow lagoon. Initially believed to be a juvenile, a deeper study of its osteology suggests it was actually fully grown.

Pholidosaurs are the group of crocodile-like reptiles that eventually gave rise to the colossal Sarcosuchus imperator which could grow up to 11 m long or more.

Article is in French:

https://www.museedesconfluences.fr/fr/ressources/crocodile-fossile

Adam Khor

Baurusuchids as top predators in Cretaceous Brazil?

Theropod dinosaurs were relatively scarce in the Late Cretaceous ecosystems of southeast Brazil. Instead, hypercarnivorous crocodyliforms known as baurusuchids were abundant and probably occupied the ecological role of apex predators

https://onlinelibrary.wiley.com/doi/10.1111/joa.13192

Baurusuchids have been called "theropod mimics", as they didn´t have the powerful, crushing bite of modern crocodilians but instead a weaker bite but sharper, blade-like teeth much like the majority of carnivorous theropods, or modern Komodo dragons. They would've been more terrestrial and probably more active and agile than modern crocodilians.

Adam Khor

Cretaceous croc Bernissartia, which coexisted with Iguanodon, was near the base of the modern crocodile family tree, study suggests:

https://www.naturalsciences.be/en/news/item/19011

Capt'n Midnight

Adam Khor wrote: »

Baurusuchids as top predators in Cretaceous Brazil?

...
They would've been more terrestrial and probably more active and agile than modern crocodilians.

Quinkana was fairly modern

It's amazing to think that some people consider Australia as a place where everything is out to get you and yet the first humans there faced real monsters.

Adam Khor

Capt'n Midnight wrote: »

Quinkana was fairly modern

It's amazing to think that some people consider Australia as a place where everything is out to get you and yet the first humans there faced real monsters.

Indeed, including not just Quinkana but also the even larger Pallimnarchus, plus all the other non-crocodilian beauties!

Adam Khor

Phytosaurs (Triassic reptiles that were not crocodilians but similar in ecology and body plan, having existed before true crocs) may have cared for their young, suggests fossil aggregation from India :

https://www.tandfonline.com/doi/abs/10.1080/02724634.2019.1726361?journalCode=ujvp20