[ad_1]
Today the southwest coast of the Isle of Wight in the UK is a picturesque seascape framed by sandstone cliffs. But over 125 million years ago, that sight was a savanna-like valley cut off by rivers and floodplains – an ideal home for two towering new dinosaurs with sleek crocodile-like skulls.
Scientists gave them corresponding names: Lower Ceratosuchops roughly translates to “crocodile-faced, horned hell heron”, drawing inspiration from propositions that spinosaurids were shore predators like today’s herons. Riparovenator milnerae Means “Milner’s Shoreline Hunter” in homage to British spinosaurid expert Angela Milner.
The bones of both species are fragmentary, but they add crucial diversity to the ranks of spinosaurids, which are poorly understood and had bizarre anatomical features, such as crocodile muzzles and the occasional giant sails on their backs.
Fossil discoveries could also shed light on the evolutionary origins of spinosaurids by specifying the group’s family tree with greater precision. This, in turn, may help paleontologists who study the iconic dinosaur Spinosaurus, which made its home in the river systems of what is now North Africa over 95 million years ago.
For study lead author Chris Barker, a Ph.D. candidate at the University of Southampton, the study is the pinnacle of a lifetime of fascination with carnivorous dinosaurs. As a young child he regularly visited the Natural History Museum in London, gazing in awe at a cast of spinosaurids Baryonyx– one of the closest relatives to Barker’s new discoveries.
“To be able to study something that you almost idolized as a child, I recognize how privileged I am today,” he says.
The newly described fossils highlight how many dinosaurs still remain to be found. Ceratosuchops and Repairer originate from the Wessex Formation, which is part of a larger set of rock layers that paleontologists have combed through since the early 1800s.
“We are still, in many ways, in our infancy in our knowledge of the diversity of ancient dinosaurs,” says University of Maryland paleontologist Tom Holtz, a spinosaurid expert who was not involved in the news. study. “We haven’t reached a plateau, even for what we consider to be well-studied training!
Spinosaur hunt
Although spinosaurid fossils have been known for over a century, rebuilding animals has been decades of work. Fossils are rare and often fragmentary; the first known bones of Spinosaurus were destroyed during World War II, hampering efforts to study the creature.
In 1986, British paleontologists Alan Charig and Angela Milner reported that the rocks of Surrey, England, had yielded a largely complete spinosaurid that lived around 129 to 125 million years ago. This fossil, named Baryonyx walkeri, confirmed that the spinosaurids had smooth crocodile-like skulls, large front claws, and long, slender necks. Baryonyx Now serves as a key reference for spinosaurids, helping to complement other details that have since been found in Spain, Brazil, Thailand, Morocco, Niger and Australia.
In the decades that followed, the rocks of southern England hinted that Baryonyx was not the only local spinosaurid. For example, spinosaurid teeth found in rocks in the area came in a variety of shapes and forms, which may be variation from individual to individual, but possibly also a sign of several species roaming the rocks.
Enter Neil Gostling, an evolutionary biologist at the University of Southampton. Gostling was working on forming a partnership with the Isle of Wight’s Dinosaur Isle Museum when he learned the museum had acquired fossils found in Chilton China, a nearby coastal ravine surrounded by ancient sandstone cliffs. In 2019, Barker started his doctorate. under Gostling and decided to take the bones for his research.
For several years, Barker carefully noted many different anatomical features across the bones and compared these features with those of known spinosaurids. When he and his colleagues ran computer models on this data, they discovered that the Isle of Wight remains likely represented two different types of spinosaurids, both closely related to Baryonyx and a spinosaurid from Niger called Suchomimus.
Towards the end of the project, Barker, Gostling and their colleagues set up an email chain to prepare the names of the new dinosaurs. Milner had died in August at the age of 73, after a distinguished career at the UK Museum of Natural History. The team agreed that honoring him “just seemed like the right thing to do,” Gostling said. “She was the person who really put it forward and made the spinosaurs a bunch that people understood and knew.”
Strange migrations
For now, it is not clear whether Ceratosuchops and Repairer overlapping in time with each other or with Baryonyx. The bones of the new dinosaurs fell from the exposed cliffs, making it all the more difficult to know what exact rock layers buried them – information that would more accurately date the bones. The best estimate is that the two new species lived around 129 to 125 million years ago during the early Cretaceous period.
Still, the new study sheds light on the movement of spinosaurids through ancient Earth. When Barker and his colleagues created an updated family tree for the group, they discovered that most of the oldest species near the base of the tree lived in what is now Europe.
This discovery reinforces the idea that the ancestral homeland of the spinosaurids was in the northern hemisphere, possibly in Europe. If so, the spinosaurids migrated to what is now Africa at least twice: a wave that produced the Suchomimus, and a later second wave which gave rise to Spinosaurus and his North African parents.
But if spinosaurids have appeared in Europe, a major dino-mystery is deepening. For much of the Dinosaur Age, Europe, Asia, and North America were connected. Spinosaurid remains have been found in Europe and Asia, but no clear fossil evidence of the group has ever been found in North America.
The absence of North American spinosaurids is all the more disconcerting as other groups of dinosaurs clearly had no problem moving between North America and Asia during this time. There is no clear sign that spinosaurids would have run out of real estate in North America. The rock formations of Montana, Wyoming, Utah, Texas, and Maryland all date back to when spinosaurids lived elsewhere, and they preserve preferred coastal or riverine habitats for spinosaurids.
“There’s nothing really super special that could have excluded them, so yeah, that’s a curious fact,” says Holtz. “All we have to do is find a tooth. “
Back on the Isle of Wight, Barker and Gostling’s work on spinosaurids has only just begun. Barker notes that the fossils of Ceratosuchops and Repairer include parts of the dinosaurs ‘skulls, which means that future analyzes of the fossils could provide data on the shape of the animals’ brains.
They add that the Isle of Wight has delivered more spinosaurid fossils waiting to be described, materials that will remain with Ceratosuchops and Repairer at the Dinosaur Isle Museum, a science destination and cultural landmark for the Isle of Wight.
“We cannot stress how important it is to have a dinosaur museum – a functioning and appropriate dinosaur museum – on the Isle of Wight for the dinosaurs on the Isle of Wight,” Gostling said. “They are not sent elsewhere in the world. They are where they were found.
[ad_2]
Source link