A group of paleontologists from Oklahoma State College, the College of Toronto and Royal Ontario Museum has added one other species of caenagnathid oviraptorosaurian dinosaur to the prehistoric catalog: Eoneophron infernalis.
An artist’s depiction of Eoneophron infernalis (prime left), Anzu wyliei (proper) and one other caenagnathid dinosaur (backside left) within the Hell Creek Formation. Picture credit score: Zubin Erik Dutta.
Eoneophron infernalis lived in what’s now the US in the course of the Late Cretaceous epoch, between 68 and 66 million years in the past.
The fossilized stays of the species had been collected from exposures of the Hell Creek Formation in South Dakota.
These sediments resemble these of typical floodplain deposits resembling siltstones with natural materials as seen elsewhere within the Hell Creek Formation.
“Once we first examined the bones, we recognized them as belonging to a household of dinosaurs often called Caenagnathidae, a bunch of birdlike dinosaurs that had toothless beaks, lengthy legs and quick tails,” stated Oklahoma State College paleontologist Kyle Atkins-Weltman and colleagues.
“Direct fossil and inferred proof signifies these dinosaurs had been lined in complicated feathers, very like fashionable birds.”
“The one identified species of caenagnathid from this time and area was Anzu. Lined in feathers and sporting wings and a toothless beak, Anzu was between 200 and 340 kg.”
“Regardless of its fearsome nickname, although, its weight loss program is a matter of debate. It was doubtless an omnivore, consuming each plant materials and small animals.”
“As a result of our specimen was considerably smaller than Anzu, we merely assumed it was a juvenile.”
“We chalked up the anatomical variations we seen to its juvenile standing and smaller dimension — and figured the animal would have modified had it continued to develop.”
“Anzu specimens are uncommon, and no particular juveniles have been revealed within the scientific literature, so we had been excited to probably be taught extra about the way it grew and adjusted all through its lifetime by trying inside its bones,” the researchers stated.
“Similar to with a tree’s rings, bone information rings referred to as strains of arrested development. Every annual line represents a part of a yr when the animal’s development slowed. They’d inform us how previous this animal was, and how briskly or gradual it was rising.”
“We minimize by way of the center of three of the bones in order that we might microscopically study the interior anatomy of the cross-sections. What we noticed utterly uprooted our preliminary assumptions.”
“In a juvenile, we might anticipate strains of arrested development within the bone to be extensively spaced, indicating fast development, with even spacing between the strains from the within to the surface floor of the bone,” they defined.
“Right here, we noticed that the later strains had been spaced progressively nearer collectively, indicating that this animal’s development had slowed and it was almost at its grownup dimension.”
“This was no juvenile. As an alternative, it was an grownup of a wholly new species, which we dubbed Eoneophron infernalis.”
Eoneophron infernalis has implications for the ecology and variety of caenagnathids within the newest Cretaceous interval.
As many as three caenagnathid species of various physique dimension could have inhabited the ecosystems of the Hell Creek Formation, however like in different areas, a poor fossil document makes untangling the taxonomy of those species problematic.
The ecology of caenagnathid dinosaurs likewise stays poorly understood, however Eoneophron infernalis expands the vary of variation inside Caenagnathidae and means that their variety in Laurasia remained largely secure between 84 and 66 million years in the past, and these dinosaurs remained profitable parts of Laurasian ecosystems till the end-Cretaceous extinction.
“With this new proof, we began making thorough comparisons with different family members to find out the place Eoneophron infernalis match throughout the group,” the scientists stated.
“It additionally impressed us to reexamine different bones beforehand believed to be Anzu, as we now knew that extra caenagnathid dinosaurs lived in western North America throughout that point.”
“Our new discovery means that this dinosaur group was not declining in variety on the very finish of the Cretaceous.”
“These fossils present that there are nonetheless new species to be found, and help the concept no less than a part of the sample of lowering variety is the results of sampling and preservation biases.”
The invention of Eoneophron infernalis is reported in a paper within the journal PLoS ONE.
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Okay.L. Atkins-Weltman et al. 2024. A brand new oviraptorosaur (Dinosauria: Theropoda) from the end-Maastrichtian Hell Creek Formation of North America. PLoS ONE 19 (1): e0294901; doi: 10.1371/journal.pone.0294901
