[PaleoOrnithology • 2017] Chupkaornis keraorum • The Oldest Asian Hesperornithiform from the Upper Cretaceous of Japan, and the Phylogenetic Reassessment of Hesperornithiformes

Chupkaornis keraorum

 Tanaka, Kobayashi, Kurihara, Fiorillo & Kano, 2017

 DOI: 10.1080/14772019.2017.1341960  

Abstract

Asian hesperornithiforms are extremely rare in contrast to the much more abundant record from North America. In Asia, these fossil birds are only known from fragmentary materials from Mongolia. Here we describe the skeletal remains of a new hesperornithiform Chupkaornis keraorum gen. et sp. nov. from the Upper Cretaceous Kashima Formation (Coniacian to Santonian) of the Yezo Group in Mikasa City, Hokkaido, Japan. This is the best-preserved hesperornithiform material from Asia and it is the first report of hesperornithiforms from the eastern margin of the Eurasian continent. Chupkaornis has a unique combination of characters: finger-like projected tibiofibular crest of femur, deep, emarginated lateral excavation with a sharply defined edge of the ventral margin of the thoracic vertebrae, and the heterocoelous articular surface of the thoracic vertebrae. Our new phylogenetic analysis revises the phylogenetic relationships of Hesperornithiformes. In contrast to previous studies, Enaliornis is assigned as the most basal taxon and Baptornis is positioned as more derived than Brodavis. Chupkaornis is a sister taxon to the clade of Brodavis and higher taxa. Parahesperornis and Hesperornis are positioned within Hesperornithidae, the derived Hesperornithiformes. Many of the skeletal character changes are concentrated at the base of Hesperornithidae (Parahesperornis and more derived taxa), and involve the modification of the pelvic girdle and hind limb morphology (e.g. dorsal directed antitrochanter of pelvis, short and sprawled femur, including probable lobe-toed feet suggested by the specialized distal articular surface of first digit of fourth toe, and predominantly robust digit IV phalanges). These skeletal modifications are likely adaptations for foot-propelled diving behaviour.

Keywords: Hesperornithiformes, diving birds, fossil birds, Late Cretaceous, new species

 Japan's first and oldest fossil diving bird,  Chupkaornis keraorum.

Life reconstruction by Masato Hattori 

Systematic palaeontology

Avialae Gauthier, 1986

Ornithuromorpha Chiappe, 2002a

Hesperornithiformes Fürbringer, 1888

Chupkaornis gen. nov.

Etymology. Chupkaornis, from the combination of the Ainu word ‘chupka’, meaning ‘eastern’, and the Greek ‘ornis’ for bird.

Chupkaornis keraorum sp. nov.

Etymology. Named after Masatoshi and Yasuji Kera, who discovered the specimen and contributed greatly to the Mikasa City Museum. 

Holotype. MCM.A773; a partial skeleton of a single individual including four cervical and two thoracic vertebrae, the distal ends of the left and right femora, and the middle part of the right fibula. 

Locality and age. Kumaoi Creek, one branch off Lake Katsurazawa, Mikasa City, Hokkaido, Japan; Kashima Formation (Coniacian to Santonian), Upper Cretaceous Yezo Group.

 Conclusions:

A new hesperornithiform, Chupkaornis keraorum gen. et sp. nov. (MCM.A773) from the Late Cretaceous of Japan, is the first record of the group from the eastern margin of the Eurasian continent and the oldest record for this avian group from Asia. The new material is the best-preserved Asian hesperornithiform specimen recovered thus far, and provides new palaeobiogeographical insights for the broad taxonomic group as well as significant new anatomical data. Chupkaornis keraorum is diagnosed by a unique combination of characters from thoracic vertebrae and femur. 

A phylogenetic analysis suggests that C. keraorum is a basal hesperornithiform. The new taxon is more derived than Pasquiaornis and more basal than Brodavis. The present analysis also suggests new phylogenetic relationships within the Hesperornithiformes; Enaliornis is the most basal hesperornithiform, and Baptornis advenus is a more derived taxon than Brodavis. The evolutionary rate calculation indicates that the rate of change is much higher within basal members of the Hesperornithidae compared to later branches. This rate change suggests that the most important morphological changes for highly foot-propelled diving adaptation are concentrated at the base of the Hesperornithidae.

Tomonori Tanaka, Yoshitsugu Kobayashi, Ken'ichi Kurihara, Anthony R. Fiorillo and Manabu Kano. 2017. The Oldest Asian Hesperornithiform from the Upper Cretaceous of Japan, and the Phylogenetic Reassessment of Hesperornithiformes. Journal of Systematic Palaeontology. DOI: 10.1080/14772019.2017.1341960 

Amateur collectors in Japan discover country's first and oldest fossil diving bird  phy.so/421422532 via @physorg_com

[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

http://phenomena.nationalgeographic.com/2015/12/11/paleo-profile-the-smoke-hill-bird/

https://twitter.com/velezjuarbej/status/667367857186021376  @NHMLA