New Fossils of Crocodilian, Hippo-Like Species from Panama
Mar. 5, 2013 — University of Florida paleontologists have discovered remarkably well-preserved fossils of two crocodilians and a mammal previously unknown to science during recent Panama Canal excavations that began in 2009.
The two new ancient extinct alligator-like animals and an extinct hippo-like species inhabited Central America during the Miocene about 20 million years ago. The research expands the range of ancient animals in the subtropics — some of the most diverse areas today about which little is known historically because lush vegetation prevents paleontological excavations — and may be used to better understand how climate change affects species dispersal today. The two studies appear online today in the same issue of the Journal of Vertebrate Paleontology.
The fossils shed new light on scientists’ understanding of species distribution because they represent a time before the formation of the Isthmus of Panama, when the continents of North and South America were separated by oceanic waters.
“In part we are trying to understand how ecosystems have responded to animals moving long distances and across geographic barriers in the past,” said study co-author Jonathan Bloch, associate curator of vertebrate paleontology at the Florida Museum of Natural History on the UF campus. “It’s a testing ground for things like invasive species — if you have things that migrated from one place into another in the past, then potentially you have the ability to look at what impact a new species might have on an ecosystem in the future.”
The research was funded by the National Science Foundation Panama Canal Partnerships in International Research and Education project, which supports paleontological excavation of the canal during construction expected to continue through 2014.
“We’re very fortunate we could get the funding for PIRE to take advantage of this opportunity — we’re getting to sample these areas that are completely unsampled,” said Alex Hastings, lead author of the crocodilian study and a visiting instructor at Georgia Southern University who conducted the research for the project as a UF graduate student.
Researchers analyzed all known crocodilian fossils from the Panama Canal, including the oldest records of Central American caimans, which are cousins of alligators. The more primitive species, named Culebrasuchus mesoamericanus, may represent an evolutionary transition between caimans and alligators, Hastings said.
“You mix an alligator and one of the more primitive caimans and you end up with this caiman that has a much flatter snout, making it more like an alligator,” Hastings said. “Before this, there were no fossil crocodilian skulls known from Central America.”
Christopher Brochu, an assistant professor of vertebrate paleontology in the department of geoscience at the University of Iowa, said “the caiman fossil record is tantalizing,” and the new data shows there is still a long way to go before researchers understand the group.
“The fossils that are in this paper are from a later time period, but some of them appear to be earlier-branching groups, which could be very important,” said Brochu, who was not involved with the study. “The problem is, because we know so little about early caiman history, it’s very difficult to tell where these later forms actually go on the family tree.”
The new mammal species researchers described is an anthracothere, Arretotherium meridionale, an even-toed hooved mammal previously thought to be related to living hippos and intensively studied on the basis of its hypothetical relationship with whales. About the size of a cow, the mammal would have lived in a semi-aquatic environment in Central America, said lead author and UF graduate student Aldo Rincon.
“With the evolution of new terrestrial corridors like this peninsula connecting North America with Central America, this is one of the most amazing examples of the different kind of paths land animals can take,” Rincon said. “Somehow this anthracothere is similar to anthracotheres from other continents like northern Africa and northeastern Asia.”
Researchers also name a second crocodilian species, Centenariosuchus gilmorei, after Charles Gilmore, who first reported evidence of crocodilian fossils collected during construction of the canal 100 years ago. The genus is named in honor of the canal’s centennial in 2014.
Researchers will continue excavating deposits from the Panama Canal during construction to widen and straighten the channel and build new locks. The project is funded by a $3.8 million NSF grant to develop partnerships between the U.S. and Panama and engage the next generation of scientists in paleontological and geological discoveries along the canal.
Study co-authors include Bruce MacFadden of UF and Carlos Jaramillo of the Smithsonian Tropical Research Institute.
New Dinosaur Species: First Fossil Evidence Shows Small Crocs Fed On Baby Dinosaurs
Feb. 28, 2013 — A South Dakota School of Mines & Technology assistant professor and his team have discovered a new species of herbivorous dinosaur and today published the first fossil evidence of prehistoric crocodyliforms feeding on small dinosaurs.
Research by Clint Boyd, Ph.D., provides the first definitive evidence that plant-eating baby ornithopod dinosaurs were a food of choice for the crocodyliform, a now extinct relative of the crocodile family. While conducting their research, the team also discovered that this dinosaur prey was a previously unrecognized species of a small ornithopod dinosaur, which has yet to be named.
The evidence found in what is now known as the Grand Staircase Escalante-National Monument in southern Utah dates back to the late Cretaceous period, toward the end of the age of dinosaurs, and was published today in the online journal PLOS ONE. The complete research findings of Boyd and Stephanie K. Drumheller, of the University of Iowa and the University of Tennessee, and Terry A. Gates, of North Carolina State University and the Natural History Museum of Utah, can be accessed online (see journal reference below).
A large number of mostly tiny bits of dinosaur bones were recovered in groups at four locations within the Utah park — which paleontologists and geologists know as the Upper Cretaceous (Campanian) Kaiparowits Formation — leading paleontologists to believe that crocodyliforms had fed on baby dinosaurs 1-2 meters in total length.
Evidence shows bite marks on bone joints, as well as breakthrough proof of a crocodyliform tooth still embedded in a dinosaur femur.
The findings are significant because historically dinosaurs have been depicted as the dominant species. “The traditional ideas you see in popular literature are that when little baby dinosaurs are either coming out of a nesting grounds or out somewhere on their own, they are normally having to worry about the theropod dinosaurs, the things like raptors or, on bigger scales, the T. rex. So this kind of adds a new dimension,” Boyd said. “You had your dominant riverine carnivores, the crocodyliforms, attacking these herbivores as well, so they kind of had it coming from all sides.”
Based on teeth marks left on bones and the large amounts of fragments left behind, it is believed the crocodyliforms were also diminutive in size, perhaps no more than 2 meters long. A larger species of crocodyliform would have been more likely to gulp down its prey without leaving behind traces of “busted up” bone fragments.
Until now, paleontologists had direct evidence only of “very large crocodyliforms” interacting with “very large dinosaurs.”
“It’s not often that you get events from the fossil record that are action-related,” Boyd explained. “While you generally assume there was probably a lot more interaction going on, we didn’t have any of that preserved in the fossil record yet. This is the first time that we have definitive evidence that you had this kind of partitioning, of your smaller crocodyliforms attacking the smaller herbivorous dinosaurs,” he said, adding that this is only the second published instance of a crocodyliform tooth embedded in any prey animal in the fossil record.
“A lot of times you find material in close association or you can find some feeding marks or traces on the outside of the bone and you can hypothesize that maybe it was a certain animal doing this, but this was only the second time we have really good definitive evidence of a crocodyliform feeding on a prey animal and in this case an ornithischian dinosaur,” Boyd said.
The high concentrations of tiny dinosaur bones led researchers to conclude a type of selection occurred, that crocodyliforms were preferentially feeding on these miniature dinosaurs. “Maybe it was closer to a nesting ground where baby dinosaurs would have been more abundant, and so the smaller crocodyliforms were hanging out there getting a lunch,” Boyd added.
“When we started looking at all the other bones, we starting finding marks that are known to be diagnostic for crocodyliform feeding traces, so all that evidence coming together suddenly started to make sense as to why we were not finding good complete specimens of these little ornithischian dinosaurs,” Boyd explained. “Most of the bites marks are concentrated around the joints, which is where the crocodyliform would tend to bite, and then, when they do their pulling or the death roll that they tend to do, the ends of the bones tend to snap off more often than not in those actions. That’s why we were finding these fragmentary bones.”
In the process of their research, the team discovered through diagnostic cranial material that these baby prey are a new, as yet-to-be-named dinosaur species. Details on this new species will soon be published in another paper.
Fossils of dinosaur-era crocodiles found in Sahara
Five exotic crocodiles that lived alongside the dinosaurs 100 million years ago, including one sporting boar-like tusks and another with a duckbill snout, have been discovered in the Sahara.
Dinosaur Era Crocodile Fossil
Unlike their modern cousins, the ancient crocodilians were as agile on land as they were in the water.
They were reptiles like the dinosaurs, but belonged to a completely separate lineage that continues to this day.
The crocodiles once ran and swam across present-day Niger and Morocco, when the region was covered by lush plains and broad rivers.
Scientists found the newly-identified fossils at a number of sites in the Sahara desert. Many were uncovered at one location, lying on the surface of a remote and windswept stretch of rock and dunes.
Expedition leader Professor Paul Sereno, from the University of Chicago, has previously described the largest find, Sarcosuchus imperator, which measured 40 feet and weighed eight tons.
Popularly known as ”SuperCroc”, the giant carnivore was the biggest but not the strangest of the extinct creatures.
They were given nicknames by the scientists, based on their unusual physical features.
”BoarCroc” (Kaprosuchus saharicus): A 20 feet upright meat-eater with an armoured snout and three sets of dagger-shaped fangs.
”RatCroc” (Araripesuchus rattoides): Discovered in Morocco, this was a three-foot-long upright plant and grub-eater. It had a pair of lower jaw buckteeth which were used to dig for food.
”PancakeCroc” (Laganosuchus thaumastos): This animal’s fossils were found in Niger and Morocco. It was a 20-foot-long squat fish-eater with a three-foot-long pancake-flat head and spiky teeth on slender jaws.
”DuckCroc” (Anatosuchus minor): A three-foot upright species that ate fish, frogs and grubs. It had a broad, overhanging snout and a long nose. Sensory areas on the snout helped it root around shallow waters for prey.
”DogCroc” (Araripesuchus wegeneri): Fossils found in Niger included five skeletons next to each other on a single block of rock. DogCroc was a three-foot-long upright plant and grub eater with a soft, doglike forward-pointing nose.
Describing the finds in National Geographic Magazine, Prof Sereno wrote: ”My African crocs appeared to have had both upright, agile legs for bounding overland and a versatile tail for paddling in water.
”Their amphibious talents in the past may be the key to understanding how they flourished in, and ultimately survived, the dinosaur era.”
Colleague Dr Hans Larsson, from McGill University in Montreal, Canada, who discovered the bones of BoarCroc and PancakeCroc, said: ”We were surprised to find so many species from the same time in the same place.
”Each of the crocs apparently had different diets, different behaviours. It appears they had divided up the ecosystem, each species taking advantage of it in its own way.”
The scientists studied the animals’ brains by creating digital and physical casts from CT-scans, 3D X-rays.
Both DogCroc and DuckCroc had broad, spade-shaped forebrains that looked different from those of living crocodiles.
”They may have had slightly more sophisticated brain function than living crocs, because active hunting on land usually requires more brain power than merely waiting for prey to show up,” said Dr Larsson.
A paper on the finds is to appear in the journal ZooKeys. The creatures will also star in a documentary, ”When Crocs Ate Dinosaurs”, to be shown on the National Geographic Channel.
Source: telegraph.co.uk