The lumbering crocodylomorph lived during the early Cretaceous period, about 106 million years ago.
A prehistoric ancestor of the crocodile may have walked on two legs, according to a paper published on June 11 in Scientific Reports.
The new research focuses on large footprints in the Jinju rock formation in South Korea. A 2012 investigation of large, poorly defined footprints suggested that they might have come from a flying reptile called a pterosaur, but clearer footprints discovered recently changed the story. The new footprints capture the shape of the ancient creature’s toes and the texture of its skin, both of which are classically crocodilian. But the footprints had another curious feature: there were only prints from back feet.
To paleontologist Martin Lockley, who specializes in trace fossils at the University of Colorado Denver, the lack of front footprints probably means that the ancient crocodile walked only on its back legs. “We have dozens of these things, and not one sign of a front footprint, so we’re pretty convinced,” Lockley tells Science News.
The tracks are between seven and ten inches long and the animal that left them was probably similar in size to modern crocodiles. It lived during the early Cretaceous period, about 106-million years ago. (The late Cretaceous saw the lifetimes of several dinosaur celebrities like Tyrannosaurus rex, Triceratops and Iguanadon.) The muddy, lake-covered coastal area where the ancient crocodylomorphs lived was a prime location to preserve footprints, Tim Vernimmen writes for National Geographic, and thousands of tracks can be found there today.
“When Martin Lockley visited the site in November 2019, I asked him what he thought of these tracks,” Kyung Soo Kim of Chinju National University of Education in Jinju tells National Geographic. “He immediately suggested that they were of the type known as Batrachopus, a crocodylian. I didn't believe it at that time, because I couldn't imagine a bipedal crocodile. But later, I was convinced by the blunt toes, the toe pads, and the details of the skin.”
The find came as a surprise. Paleontologists have found evidence of bipedal crocodiles before in North Carolina, but that animal lived about 231 million years ago, per Science News. That places it during the Triassic period, or at least 70 million years before the Cretaceous.
“No one knew that large bipedal crocs existed in the early Cretaceous,” Lockley tells New Scientist’s Layal Liverpool.
The new footprints suggest that the previously discovered tracks belong to an ancient crocodile, too. But based on the tracks it left behind, the creature was unlike modern crocodiles in more ways than one. For one thing, the tracks it left behind show that the animal put its feet one in front of the other as it walked, instead of keeping each foot in its own lane like modern crocs, National Geographic reports. And the fossilized footprints show no sign of webbing between the toes, which modern crocs have, per New Scientist.
Stony Brook University paleontologist Pedro Godoy tells New Scientist that while he agrees that the tracks don’t belong to a pterosaur, the unusually large size of the tracks makes him think that more evidence is necessary to link them to an ancient crocodile. But to Emory University paleontologist Anthony Martin, the evidence is convincing.
“[The imprints] really do look like they were made by big crocodilians,” Martin, who was not involved in the new study, tells National Geographic. “Indeed, by ones that were walking on their rear feet and on land. That’s pretty weird. But then again, the Cretaceous was a weird and wondrous time.”
UCMP Berkely- Crocodylomorpha Taxa
The Aldabra white-throated rail bird was declared extinct, a victim of rising sea levels almost 100,000 years ago.
However, the flightless brown bird has recently been spotted – leaving scientists scratching their heads as to how – and why – the species has come back to life.
According to research in the Zoological Journal of Linnean Society, the re-incarnated Aldabra bird is a product of ‘iterative evolution’. That’s when old genes thought to have died out re-emerge at a different point in time.
That means that while a bird’s ancestors might have disappeared, that DNA still remains – and provided the environment is right, there’s nothing to stop those ancient genes from replicating in modern times.
So identical species can indeed produce multiple, slightly evolved offshoots, throughout the course of their species' history.
But don’t get your hopes up that this means dinosaurs and wooly mammoths will be popping up next. This scientific phenomenon only occurs within species that are nearly identical to their ancestors.
While iterative evolution has previously occurred in species such as turtles, it has never been seen in the realm of birds.
“We know of no other example in the rails, or of birds in general, that demonstrates this phenomenon so evidently,” said paleobiologist David Martill, in a statement.
“Only on the Aldabra, which has the oldest palaentological record of any oceanic island within the Indian Ocean region, is fossil evidence available that demonstrates the effects of changing sea levels on extinction and recolonization events.”
2020 was already an interesting and confusing year. Looks like now we have to contend with re-materializing birds, as well.
To better predict the ecological and evolutionary effects of the emerging biodiversity crisis in the modern oceans, we compared the association between extinction threat and ecological traits in modern marine animals to associations observed during past extinction events using a database of 2497 marine vertebrate and mollusc genera. We find that extinction threat in the modern oceans is strongly associated with large body size, whereas past extinction events were either nonselective or preferentially removed smaller-bodied taxa. Pelagic (coastal and middle dwelling ocenic fish) animals were victimized more than benthic (bottom dwelling) animals during previous mass extinctions but are not preferentially threatened in the modern ocean. The differential importance of large-bodied animals to ecosystem function portends greater future ecological disruption than that caused by similar levels of taxonomic loss in past mass extinction events.
Trophy Hunting Sustains, Prospers, and Preserves Wildlife Habitats and Residents- The Story Revealed
To the untrained eye, most fossils don’t appear to be bursting with color. The first scientific analysis of fossil color was published only a decade ago, and until recently, determining the color palette of the prehistoric world seemed an insurmountable task.
Maria McNamara, a paleontologist at University College Cork in Ireland, is trying to piece together the fossil evidence to paint a colorful picture of the past. When people think of paleontology, they often think of hard teeth and bone, but the softer parts of animals, like skin, muscle tissue and internal organs, can be preserved in the fossil record, too. It's much rarer, of course, because the squishy stuff usually rots away, but soft tissues are exactly the kind of specimens McNamara is looking for. She studies tissues from insects and vertebrates in order to envision what these critters looked like and how they interacted with their environments—what their predators were, where they lived, what their mating habits may have been and more.
McNamara will be discussing her work to find the color remnants in fossils at the Smithsonian's National Museum of Natural History’s "Life’s Greatest Hits: Key Events in Evolution" symposium on Friday, March 29, in Washington DC. Ahead of her talk, Smithsonian.com spoke to McNamara to learn more about the colors of the ancient world.
Read more: SMITHSONIAN.COM