New bird from the Cretaceous of Utah

[The Amateur Paleontologist]

hey everyone - hope you're all well 

 

Thought this was worth sharing - a description of a well-preserved enantiornithean bird specimen from the Late Cretaceous Kaiparowits Formation of Utah. It represents a new genus and species, Mirarce eatoni. The specimen was originally collected in 1992, but it was only recently described (and published yesterday!).

 

 

 

Atterholt et al. (2018). The most complete enantiornithine from North America and a phylogenetic analysis of the Avisauridae. PeerJ, DOI 10.7717/peerj.5910

 

Abstract:

The most complete known North American enantiornithine was collected in 1992 but never formally described. The so-called “Kaiparowits avisaurid” remains one of the most exceptional Late Cretaceous enantiornithine fossils. We recognize this specimen as a new taxon, Mirarce eatoni (gen. et sp. nov.), and provide a complete anatomical description. We maintain that the specimen is referable to the Avisauridae, a clade previously only known in North America from isolated tarsometatarsi. Information from this specimen helps to clarify evolutionary trends within the Enantiornithes. Its large body size supports previously observed trends toward larger body mass in the Late Cretaceous. However, trends toward increased fusion of compound elements across the clade as a whole are weak compared to the Ornithuromorpha. The new specimen reveals for the first time the presence of remige papillae in the enantiornithines, indicating this feature was evolved in parallel to dromaeosaurids and derived ornithuromorphs. Although morphology of the pygostyle and (to a lesser degree) the coracoid and manus appear to remain fairly static during the 65 million years plus of enantiornithine evolution, by the end of the Mesozoic at least some enantiornithine birds had evolved several features convergent with the Neornithes including a deeply keeled sternum, a narrow furcula with a short hypocleidium, and ulnar quill knobs—all features that indicate refinement of theflight apparatus and increased aerial abilities. We conduct the first cladistic analysis to include all purported avisuarid enantiornithines, recovering an Avisauridae consisting of a dichotomy between North and South American taxa. Based on morphological observations and supported by cladistic analysis, we demonstrate Avisaurus to be paraphyletic and erect a new genus for “A. gloriae,” Gettyia gen. nov.

 

here's the paper: Atterholt et al.

 

Hope you like it!

 

-Christian

 

 

[DD1991]

Pretty cool fossil bird discovery in Utah! The degree of skeletal completeness in Mirarce is quite remarkable given that most Late Cretaceous birds found in terrestrial deposits in the Western Interior tend to be based on isolated elements, unlike the classic bird taxa from the Niobrara Formation of the Midwest.   

[The Amateur Paleontologist]

8 hours ago, DD1991 said:

unlike the classic bird taxa from the Niobrara Formation of the Midwest.

And even in the Niobrara Fm., most bird remains are found in the form of isolated postcranial material  

-Christian