Sunday, December 20, 2015

[PaleoOrnithology • 2015] Fumicollis hoffmani • Identification of A New Hesperornithiform from the Cretaceous Niobrara Chalk and Implications for Ecologic Diversity among Early Diving Birds


Fumicollis hoffmani
 Bell & Chiappe. 2015
DOI: 
10.1371/journal.pone.0141690

Abstract

The Smoky Hill Member of the Niobrara Chalk in Kansas (USA) has yielded the remains of numerous members of the Hesperornithiformes, toothed diving birds from the late Early to Late Cretaceous. This study presents a new taxon of hesperornithiform from the Smoky Hill Member, Fumicollis hoffmani, the holotype of which is among the more complete hesperornithiform skeletons. Fumicollis has a unique combination of primitive (e.g. proximal and distal ends of femur not expanded, elongate pre-acetabular ilium, small and pyramidal patella) and derived (e.g. dorsal ridge on metatarsal IV, plantarly-projected curve in the distal shaft of phalanx III:1) hesperornithiform characters, suggesting it was more specialized than small hesperornithiforms like Baptornis advenus but not as highly derived as the larger Hesperornis regalis. The identification of Fumicollis highlights once again the significant diversity of hesperornithiforms that existed in the Late Cretaceous Western Interior Seaway. This diversity points to the existence of a complex ecosystem, perhaps with a high degree of niche partitioning, as indicated by the varying degrees of diving specializations among these birds.

Systematic Paleontology

Aves Linnaeus 1758
Ornithuromorpha Chiappe 2002
Ornithurae Haeckel 1866

Hesperornithiformes Fürbringer 1888

Fumicollis hoffmani gen. et sp. nov.
urn:lsid:zoobank.org:act:81992545-5F0F-4ED4-BEE4-9825ACCDE769
urn:lsid:zoobank.org:act:D8E670C5-1E02-4308-B34B-B3E1F43AABF3

Etymology: The genus name Fumicollis is from the Latin fumi (smoke) and collis (hill), in reference to the Smoky Hill Member of the Niobrara Chalk in which the specimen was discovered. The species name hoffmani is in recognition of Karen and Jim Hoffman, whose generous support has greatly enhanced the programs of the Natural History Museum of Los Angeles County, including research at the Dinosaur Institute.





Conclusions

UNSM 20030 provides us with a novel hesperornithiform, Fumicollis hoffmani, that is morphologically transitional between the smaller, more primitive Baptornis advenus and the larger, more derived Hesperornis regalis and Parahesperornis alexi. Phylogenetic analysis of F. hoffmani and other hesperornithiforms has supported an intermediate placement of F. hoffmani between B. advenus and H. regalis and P. alexi, highlighting the significance of this well-preserved specimen in furthering our understanding of the evolution of diving specializations in a group of Late Cretaceous birds. The identification of Fumicollis hoffmani, a new taxon displaying a complex mosaic of anatomical traits present in other hesperornithiforms, further illustrates the taxonomic diversity reached by these Late Cretaceous birds. Given the overlap in geologic time and space among some hesperornithiforms, including Fumicollis hoffmani, physical distinctions may have played a role in niche partitioning within the Late Cretaceous diving birds of the Western Interior Seaway of Kansas.


Alyssa Bell and Luis M. Chiappe. 2015. Identification of A New Hesperornithiform from the Cretaceous Niobrara Chalk and Implications for Ecologic Diversity among Early Diving Birds.  PLoS ONE.  DOI: 10.1371/journal.pone.0141690


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