Illustration depicting Mirace eatoni perched on a Utahceratops gettyi Illustration: Brian Engh A museum might wow you with all its…
Illustration depicting Mirace eatoni perched on a Utahceratops gettyi Illustration: Brian Engh
A museum might wow you with all its fossil specimens on display, but that’s often just a Small part of what’s really there-specimens in the back could lay in drawers or plaster-wrapped in boxes, quietly holding still-to-be-revealed secrets or further mysteries about the past. Such is the case with an incredible bird fossil, found 25 years ago in Utah but only just described.
The fossil is pretty nut-a turkey-sized extinct bird called an enantiornithine, apparently highly capable of flight, and perhaps one of The most complete of its kind ever found in North America. It furthers the mystery of why some dinosaurs went extinct but others (the birds we see today) stuck around.
The wishbone Photo: Atterholt et al (PeerJ 2018)
“The skeleton tells an interesting evolutionary story. Just before they went extinct, enantiornithine birds had separately independently evolved adaptations for advanced flight just like modern birds, “author Jessie Atterholt, assistant professor at the Western University of Health Sciences, told Gizmodo.
This fossil has a story a quarter of a century old. Paleontologist Howard Hutchison found it on a trip to the Grand Staircase Escalante National Monument in Utah, in 75-million-year-old rocks. Plenty of paleontologists knew about the “important” specimen, Atterholt explained-but never completed their analysis on it. Atterholt was specifically interested in how these enantiomithines evolved and asked if she could work on it. She, Hutchison, and researcher Jingmai O’Connor published the results today in PeerJ.
The fossil skeleton, now a new species named Mirarce eatoni, includes several vertebrae, the base of the spine that would support the tail feathers, almost all of the bones of the left foot and some from the right, a humerus, a femur, the lowest leg bone found in birds called the tarsometatarsus, a wishbone, and other pieces. It was birdy looking, and probably the size of a turkey. Perhaps most excitingly, the ulna, or forewing bone, featured little rough notches interpreted as “quill knobs.” These are features present in today’s birds that reinforce the feathers and are indicative of advanced flight, said Atterholt.
Left foot pieces Photo: Atterholt et al (PeerJ 2018)
“No doubt this is one of the most important bird fossils from the Age of Dinosaurs,” Steve Brusatte, a University of Edinburgh paleontologist not involved with the study, told Gizmodo.
This fossil tells the story of a group of birds that evolved in parallel with the forerunners of today’s modern birds, but did not make it through the mass-extinction event. De high level of preserved detail further demonstrates that a ton of diversity failed to make it pass the asteroid strike. But it deepens the mystery. Na de meteor, leverden slechts een paar vogels, die dan gediversifieerd in de 10.000 soorten rond vandaag. Brusatte elaborated on the mystery:
“Maybe they had beaks and could eat seeds-a nutritious food source that can survive in the soil for decades or centuries, a food bank for when the world went to hell when the asteroid hit. Or maybe these birds nested on the ground, so they were not wiped out with the tree-living birds when forests collapsed after the asteroid hit. Or maybe they could fly longer, or grow faster, or hide easier. We do not really know. Men denne nye discovery fortæller os at de fugle, der levede med de sidste dinosaurerne, var lige mere forskellige end vi brugte til at tænke, så det er mere af et mysterium hvorfor så få af dem overlevede asteroiden. “
All of the bones found  Illustration: Scott Hartman
Atterholt is continuing to research these bones to study what the bird was like and how it evolved. She also mentioned the recent controversy about the site from which the fossil originated, Grand Staircase Escalante. Recently, President Trump reduced the size of this national monument.
“This material would be at risk of destruction and threat from reducing the size of the protected lands.”