Guest Post: Yurgovuchia doellingi

Those keeping up with the scientific literature will know that a new dromaeosaur was described just the other day. One of the authors, Jim Kirkland, has been kind enough to pen a few lines about the discovery and has included some nice photos of the excavation too. Enjoy:
Even partial dinosaur skeletons without feathers are important. This week we reported on fossil remains representing three distinct small dromaeosaur taxa from the lowest part of the Early Cretaceous section on US Bureau of Land Management land in eastern Utah. Only one of these provided enough diagnostic material to name; Yurgovuchia doellingi.
The species name honors Helmut Doelling in recognition of his more than 50 years of geological research and geological mapping of Utah for the UGS. The genus name is derived from the Ute word yurgovuch, meaning coyote, a predator of similar size to Y. doellingi that currently inhabits the same region.

Helmut Doelling with Yurgovuchia doellingi

Y. doellingi was found in Doellings Bowl Bone Bed; an extensive and important dinosaur site that was first discovered as a result of Doelling providing taped-together color photocopies of his then-unpublished geological maps of the Arches National Park region to an unknown young paleontologist named Jim Kirkland in 1990. This map revealed a number of unexplored areas resulting in the discovery of this important dinosaur bone bed. The locality is particularly important as it sits below a marker bed that had formerly been used to mark the base of the Cretaceous and is thus older than previously studied Lower Cretaceous dinosaur sites in the area. So… be kind and you might get a dinosaur named after you.

Don DeBlieux at the locality

Y. doellingi was initially discovered in 2005 by UGS paleontologist Don DeBlieux when he found the partial vertebral column and part of the pelvis. A second species is represented by a part of the pelvis and a possibly-associated arm bone. Simultaneously,  UGS paleontologist Scott Madsen were investigating bones of an iguanodont about 100 meters north and I was excavating a polacanthine ankylosaur spine at my initial 1991 tooth and scute locality approximately two hundred meters to the west. All of these sites were later found to be portions of the same extensive bone bed larger than that of Dinosaur National Monument.

The Doelling’s Bowl Bonebed is particularly important as it sits below a marker calcrete bed that had formally been used to mark the base of the Cretaceous and is thus older than previously studied Lower Cretaceous Dinosaur Sites in the area. Several additional new dinosaur species (iguanodonts, sauropods, carnosaurs, polacanthine ankylosaurs and hypsilophodonts) are being excavated by the UGS at this site and are under study.

Isolated bones on the surface

These new dinosaurs are from the Yellow Cat Member of the Cedar Mountain at the base of the Cretaceous in eastern Utah. These rocks have yielded an exciting new suite of dinosaurs in the last few years, whose rouges gallery of newly named theropods  (meat-eating dinosaur) species, in addition to Yurgovuchia, includes coelurosaur Nedcolbertia justinhofmanni, and the giant dromaeosaurid Utahraptor ostrommaysorum from above the calcrete and  the therizinosauroid Falcarius utahensis, the troodontid Geminiraptor suarezarum from below a distinctive “caprock” about 40 kilometers to the west. Unfortunately. we still have no means of correlating the “caprock” with the marker calcrete and still have no dinosaur species in common from the basal Yellow Cat Mbr. in the two areas.

The new tail described in this paper is from above the marker calcrete bed and recovered from Andrew’s Site, a locality a few miles to the west that yielded the iguanodont Hippodraco that was formally named in 2010. Andrew’s Site was discovered by Andrew Milner paleontologist at the St. George Dinosaur Discovery Site at Johnson Farm. This tail is distinctive in the long extensions of bone off of each vertebrae stiffing the tail as a balancing organ. Although not providing enough information to permit the species to be properly defined, the fossil proves that there were more advanced dromaeosaurs like Velociraptor and Deinonychus living in the same habitats as the giant but more primitive Utahraptor.

The tail under natural and UV light.

The paper describing these new dinosaurs “New dromaeosaurids (Dinosauria: Theropoda) from the Lower Cretaceous of Utah and the evolution of the dromaeosaurid tail” was published yesterday in PLos One (Public Library of Science) as part of a collaboration between UGS paleontologists and Phil Senter, from Fayetteville University in North Carolina. I have two admit I’m troubled that Deinonychus, with its more derived tail, forms a clade with Utahraptor and Yurgovuchia among the dromaeosaurines in Phil Senter’s phylogenetic analysis, but such things change with recognition of new character states.

5 Responses to “Guest Post: Yurgovuchia doellingi”

  1. 1 Mickey Mortimer 17/05/2012 at 4:59 pm

    “I have two admit I’m troubled that Deinonychus, with its more derived tail, forms a clade with Utahraptor and Yurgovuchia among the dromaeosaurines in Phil Senter’s phylogenetic analysis, but such things change with recognition of new character states.”

    But the “derived” tail is actually symplesiomorphic, since it’s shared with velociraptorines, saurornitholestines and microraptorines. So unless you think derived dromaeosaurines were basal to a clade containing those subfamilies, they’d be expected to have sister taxa with caudothecae.

    I’m curious what the evidence is for hemicaudothecae in dromaeosaurines besides Yurgovuchia. In Achillobator, the prezygapophyses extend at least 1.5 times centrum length, and Perle et al. (1999) do not state they are incomplete. No described caudals of Utahraptor have prezygapophyses complete enough to even be sure they extended more than one centrum length. Do the undescribed specimens have complete prezygapophyses, and if so, how many centra do they overlap?

  2. 2 Zhen 18/05/2012 at 5:01 am

    How would one go about pronouncing Yurgovuchia doellingi? This is one of the most head scratching names I’ve encountered this year.

  3. 4 James I. Kirkland 18/05/2012 at 4:18 pm

    Utahraptor’s tail is much like Yurgavuchia and Achillobator based on isolated caudals.velociraptorines overlap several vertebra..

  4. 5 Mickey Mortimer 19/05/2012 at 8:33 pm

    Thanks, but I was hoping to learn how we know the prezygapophyses of Achillobator are complete, since I’m pretty sure Senter hasn’t seen the specimen, and would be interested in getting a number for how many centra are overlapped by Utahraptor’s.

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