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Armadillosuchus arrudai
#1
Armadillosuchus arrudai

[Image: article-1198284-05A0B245000005DC-84.jpg]

Fossil range: Late Cretaceous 

Scientific classification 
Kingdom: Animalia 
Phylum: Chordata 
Class: Sauropsida 
Superorder: Crocodylomorpha 
Suborder: Notosuchia 
Family: Sphagesauridae 
Genus: Armadillosuchus
Species: Armadillosuchus arrudai

Armadillosuchus is an extinct genus of sphagesaurid crocodylomorph. It was described in February 2009 from the Late Cretaceous Bauru Basin of Brazil. Sphagesaurids share a number of mammal-like features in their teeth and jaws, although they are unrelated to mammals. Armadillosuchus is especially mammal-like in that it had heavy body armor characterized by flexible bands and rigid shields that covered its back, less like the traditional osteoderms that line the backs of most crurotarsans and more like that of a modern armadillo (hence the genus name meaning "armadillo crocodile"). Because of its unique morphology, it is believed to have had a terrestrial and quite possibly fossorial lifestyle.

[Image: article-1198284-05A0B330000005DC-79.jpg]



Armadillo-like Crocodile Fossil Found in Brazil

John Roach
for National Geographic News
July 8, 2009


An ancient fossil crocodile coated in armadillo-like body armor was unveiled yesterday at an environmental museum in Brazil. 

Dubbed Armadillosuchus arrudai, the newly described species of crocodile roamed the arid interior of Brazil about 90 million years ago, during the late Cretaceous period, scientists said. 

It was 6.6 feet (2 meters) long, weighed about 265 pounds (120 kilograms), and had a relatively wide head with a narrow, toothy snout. 

Body armor has never been "found in any other fossil or living crocodile species," Ismar de Souza Carvalho, a paleontologist at the Federal University in Rio de Janeiro, said via email. 

And "the strangeness did not stop there," Thiago Marinho, a paleontologist with the Federal University, added in an email. "This crocodyliform could [chew] like mammals do, like we do." 

Most modern crocs simply use their powerful jaws to clamp down on their prey. But the fossil crocodile could move its lower jaw forward and backward, using its teeth to tear into dried meat, roots, pine branches, and mollusks, Marinho said. 

[Image: armadillosuchus2B1.jpg]

Hot, Dry Climate 

Paleontologists found the creature in 2005 in the Bauru region of São Paolo state, an area thought to have been hot and dry about 90 million years ago, noted de Souza Carvalho. 

"Rainfall was seasonal, with flash-flood rivers. This is also uncommon to the living crocodiles and alligators that generally live in permanent waters," he said. 

Armadillosuchus' arms and hands were likely capable of digging into the soil like those of armadillos. 

"This could be a strategy to avoid dehydration in the arid environment—excavating holes in the soil—or to avoid other large crocodyliforms of that time," de Souza Carvalho said. 

The team described the fossils in the February 2009 issue of the Journal of South American Earth Sciences. The fossils and life-like reconstructions went on display Tuesday at the Museu do Meio Ambiente do Jardim Botânico do Rio de Janiero.

http://news.nationalgeographic.com/news/...razil.html




Journal Reference:
Marinho, Thiago S.; Carvalho, Ismar S. (2009). "An armadillo-like sphagesaurid crocodyliform from the Late Cretaceous of Brazil". Journal of South American Earth Sciences 27 (1): 36–41. doi:10.1016/j.jsames.2008.11.005.

Abstract
The Sphagesauridae is a family of Crocodyliformes exclusively known for the Brazilian Late Cretaceous
Bauru Basin. This lineage reveals how diverse was the morphology and ecology of terrestrial Crocodyliformes
during the Late Cretaceous of Gondwana. Here is described Armadillosuchus arrudai gen. et sp.
nov., a sphagesaurid that presents some mammal-like morphological features, such as propalinal and
alternate unilateral jaw occlusion pattern and heavy body armor, composed of a rigid shield and
mobile-banded section as in extant armadillos (Xenarthra, Dasypodidae). These unusual morphological
features contrast to the double row of osteoderms observed on the closest relatives of A. arrudai. As its
mammal analogs, A. arrudai presents some evidence of fossoriality and an exclusive terrestrial life style
in contrast to the extant alligatorids and crocodylids.

Attached to this post:[Image: attach.png] An_armadillo_like_sphagesaurid_crocodyliform_from_the_Late_Cretaceous_of_Brazil.pdf (1.56 MB)
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#2
Some extinct crocs were vegetarians

by University of Utah

[Image: 1-someextinctc.jpg]
Life reconstructions of extinct crocodyliforms. Differences in tooth shape are related to differences in diets. Credit: Jorge Gonzalez

Based on careful study of fossilized teeth, scientists Keegan Melstom and Randall Irmis at the Natural History Museum of Utah at the University of Utah have found that multiple ancient groups of crocodyliforms—the group including living and extinct relatives of crocodiles and alligators—were not the carnivores we know today, as reported in the journal Current Biology on June 27. In fact, the evidence suggests that a veggie diet arose in the distant cousins of modern crocodylians at least three times.
"The most interesting thing we discovered was how frequently it seems extinct crocodyliforms ate plants," said Keegan Melstrom, a doctoral student at the University of Utah. "Our study indicates that complexly-shaped teeth, which we infer to indicate herbivory, appear in the extinct relatives of crocodiles at least three times and maybe as many as six."
All living crocodylians possess a similar general body shape and ecology to match their lifestyle as semiaquatic generalist carnivores, which includes relatively simple, conical teeth. It was clear from the start of the study that extinct species showed a different pattern, including species with many specializations not seen today. One such specialization is a feature known as heterodonty: regionalized differences in tooth size or shape.
"Carnivores possess simple teeth whereas herbivores have much more complex teeth," Melstrom explained. "Omnivores, organisms that eat both plant and animal material, fall somewhere in between. Part of my earlier research showed that this pattern holds in living reptiles that have teeth, such as crocodylians and lizards. So these results told us that the basic pattern between diet and teeth is found in both mammals and reptiles, despite very different tooth shapes, and is applicable to extinct reptiles."
To infer what those extinct crocodyliforms most likely ate, Melstrom and his graduate advisor, chief curator Randall Irmis, compared the tooth complexity of extinct crocodyliforms to those of living animals using a method originally developed for use in living mammals. Overall, they measured 146 teeth from 16 different species of extinct crocodyliforms.
Using a combination of quantitative dental measurements and other morphological features, the researchers reconstructed the diets of those extinct crocodyliforms. The results show that those animals had a wider range of dental complexities and presumed dietary ecologies than had been appreciated previously.

[Image: someextinctc.jpg]
False color 3D images showing the range in shape of crocodyliform teeth. Carnivores (left), such as the living Caiman, have simple teeth, whereas herbivores (right) have much more complex teeth. Credit: Keegan Melstrom/NHMU

Plant-eating crocodyliforms appeared early in the evolutionary history of the group, the researchers conclude, shortly after the end-Triassic mass extinction, and persisted until the end-Cretaceous mass extinction that killed off all dinosaurs except birds. Their analysis suggests that herbivory arose independently a minimum of three times, and possibly six times, in Mesozoic crocodyliforms.
"Our work demonstrates that extinct crocodyliforms had an incredibly varied diet," Melstrom said. "Some were similar to living crocodylians and were primarily carnivorous, others were omnivores and still others likely specialized in plants. The herbivores lived on different continents at different times, some alongside mammals and mammal relatives, and others did not. This suggests that an herbivorous crocodyliform was successful in a variety of environments!"
Melstrom says they are continuing to reconstruct the diets of extinct crocodyliforms, including in fossilized species that are missing teeth. He also wants to understand why the extinct relatives of crocodiles diversified so radically after one mass extinction but not another, and whether dietary ecology could have played a role.

https://phys.org/news/2019-06-extinct-cr...rians.html



Journal Reference:
Current Biology, Melstrom and Irmis: "Repeated Evolution of Herbivorous Crocodyliforms during the Age of Dinosaurs" https://www.cell.com/current-biology/ful...19)30690-6 , DOI: 10.1016/j.cub.2019.05.076

Summary
Extinct crocodyliforms from the age of dinosaurs (Mesozoic Era) display an impressive range of skeletal morphologies, suggesting a diversity of ecological roles not found in living representatives. In particular, unusual dental morphologies develop repeatedly through the evolutionary history of this group. Recent descriptions of fossil crocodyliforms and their unusual teeth provide the inferential basis for a wide range of feeding ecologies. However, tests of these hypotheses are hindered by the lack of directly comparable dental morphologies in living reptiles and mammals, thereby preventing an accurate ecosystem reconstruction. Here, we demonstrate, using a combination of the orientation patch count rotated method and discrete morphological features, that Mesozoic crocodyliforms exploited a much greater range of feeding ecologies than their extant relatives, including likely omnivores and herbivores. These results also indicate that crocodyliforms independently developed high-complexity dentitions a minimum of three times. Some taxa possess teeth that surpass the complexities of living herbivorous lizards and rival those of omnivorous and herbivorous mammals. This study indicates that herbivorous crocodyliforms were more common than previously thought and were present throughout the Mesozoic and on most continents. The occurrence of multiple origins of complex dentitions throughout Crocodyliformes indicates that herbivory was a beneficial dietary strategy and not a unique occurrence. Many of these crocodyliforms lived alongside omnivorous or herbivorous synapsids, illustrating an ecological partition that is not observed today.

https://www.cell.com/current-biology/ful...all%3Dtrue
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