The fossil skull that could rewrite the history of Earth's continents: Remains of primitive mammal discovered in Utah suggest Pangea supercontinent split much later than previously thought
- Scientists discovered the skull of an animal underneath a dinosaur bone in Utah
- It has revealed supercontinent Pangea split much later than previously thought
- New species named Cifelliodon wahkarmoosuch and lived 130 million years ago
A fossilized skull of a small critter found in Utah underneath a dinosaur foot bone has scientists rethinking the timing of the break-up of Earth's bygone supercontinent Pangea.
On Wednesday scientists discovered the nearly 130-million-year-old fossilized skull of a primitive Cretaceous Period mammal called Cifelliodon wahkarmoosuch, about the size of a small hare.
The fossil is evidence that the super-continental split likely occurred much more recently than scientists had previously thought, about 15 million years later than previously believed.
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A fossilized skull of a small critter found in Utah underneath a dinosaur foot bone has scientists rethinking the timing of the break-up of Earth's bygone supercontinent Pangea
'Based on the unlikely discovery of this near-complete fossil cranium, we now recognize a new, cosmopolitan group of early mammal relatives,' said Adam Huttenlocker, lead author of the study and assistant professor of clinical integrative anatomical sciences at the Keck School of Medicine of USC.
'For a long time, we thought early mammals from the Cretaceous (145 to 66 million years ago) were anatomically similar and not ecologically diverse,' Huttenlocker said.
'This finding by our team and others reinforce that, even before the rise of modern mammals, ancient relatives of mammals were exploring specialty niches: insectivores, herbivores, carnivores, swimmers, gliders.
'Basically, they were occupying a variety of niches that we see them occupy today.'
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Before a geological process called plate tectonics rendered them separate land masses, the Americas, Eurasia, Africa, Antarctica, Australia and India all were part of a huge, single continent called Pangea.
The timing for Pangea's breakup, initially into two major land masses, has been a matter of scientific debate.
The study reveals that the early mammal precursors migrated from Asia to Europe, into North America and further onto major Southern continents, said Zhe-Xi Luo, senior author of the study and a paleontologist at the University of Chicago.
The most recent supercontinent, Pangea (Greek for ‘All Lands’), is thought to have formed about 300 million years ago with Africa at its center
'It's a plant eater, as we can tell from its herbivorous teeth,' said Luo.
'From the sediments in which it was preserved, likely it lived on the banks or flood plain of a small river.'
The three-inch (7.5-cm) skull was well preserved and nearly complete, unlike the usual scrappy fossils of the group to which Cifelliodon belonged, called haramiyidans.
The earliest primitive mammals evolved during the Triassic Period, when dinosaurs also first appeared, from creatures that combined reptilian and mammalian characteristics.
Haramiyidans appeared close to the dawn of the mammalian lineage, with the earliest-known representative living about 208 million years ago and the last-known member perhaps about 70 million years ago.
The skull was unwittingly excavated at a site north of Arches National Park in eastern Utah.
On Wednesday scientists discovered the nearly 130-million-year-old fossilized skull of a primitive Cretaceous Period mammal called Cifelliodon wahkarmoosuch, about the size of a small hare
The paleontologists from Utah Geological Survey did not know it was entombed in rock brought back to a lab for study until they looked under a foot bone of a two-legged plant-eating dinosaur called Hippodraco.
It may be the best-preserved skull of any haramiyidan, offering a new understanding of the group.
'Compared to modern mammals, Cifelliodon had a simple, tube-like brain, lacked complex bony structures usually associated with the front part of the brain case and nasal region, and had simple tooth roots, among other primitive features,' Huttenlocker said.
The researchers said the discovery of Cifelliodon, which had a close contemporaneous relative in Africa, suggests there were still connections between the northern hemisphere continents and those in the southern hemisphere 15 million years later than previously believed.
KILLING OFF THE DINOSAURS: HOW A CITY-SIZED ASTEROID WIPED OUT 75 PER CENT OF ALL ANIMAL AND PLANT SPECIES
Around 66 million years ago non-avian dinosaurs were wiped out and more than half the world's species were obliterated.
This mass extinction paved the way for the rise of mammals and the appearance of humans.
The Chicxulub asteroid is often cited as a potential cause of the Cretaceous-Paleogene extinction event.
The asteroid slammed into a shallow sea in what is now the Gulf of Mexico.
The collision released a huge dust and soot cloud that triggered global climate change, wiping out 75 per cent of all animal and plant species.
Researchers claim that the soot necessary for such a global catastrophe could only have come from a direct impact on rocks in shallow water around Mexico, which are especially rich in hydrocarbons.
Within 10 hours of the impact, a massive tsunami waved ripped through the Gulf coast, experts believe.
Around 66 million years ago non-avian dinosaurs were wiped out and more than half the world's species were obliterated. The Chicxulub asteroid is often cited as a potential cause of the Cretaceous-Paleogene extinction event (stock image)
This caused earthquakes and landslides in areas as far as Argentina.
While investigating the event researchers found small particles of rock and other debris that was shot into the air when the asteroid crashed.
Called spherules, these small particles covered the planet with a thick layer of soot.
Experts explain that losing the light from the sun caused a complete collapse in the aquatic system.
This is because the phytoplankton base of almost all aquatic food chains would have been eliminated.
It's believed that the more than 180 million years of evolution that brought the world to the Cretaceous point was destroyed in less than the lifetime of a Tyrannosaurus rex, which is about 20 to 30 years.
They named the fossil after famed paleontologist Richard Cifelli.
The species name, 'wahkarmoosuch' means 'yellow cat' in the Ute tribe's language in respect of the area where it was found.
"The skull of Cifelliodon is an extremely rare find in a vast fossil-bearing region of the Western Interior, where the more than 150 species of mammals and reptile-like mammal precursors are represented mostly by isolated teeth and jaws," said James Kirkland, study co-author in charge of the excavation and a Utah State paleontologist.
It boasts traits suggesting it possessed a keen sense of smell and may have been nocturnal. The research was published in the journal Nature.
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