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Describer Marsh, 1872 Time Cretaceous Late Coniacian Santonian Campanian Maastrichtian Classification Saurischia Theropoda Tetanurae Coelurosauria Maniraptora Avialae Ornithothoraces Ornithurae [Hesperonithiformes]
Fossilsite Niobrara Chalk Formation, Kansas; Pierre Shale, Nebraska, US; Vermillion River Formation, Manitoba; Foremost Formation, Alberta, Kanguk Formation, NW Territories; Canada Info Hesperornis regalis (Marsh, 1872) (= [Hargeria] Lucas, 1903; [Lestornis] Marsh, 1876) > Hesperornis crassipes (Marsh, 1876) [= Lestornis crassipes (Marsh, 1876)] > Hesperornis gracilis (Marsh, 1876) [= Hargeria gracilis (Marsh, 1876)] Dozens of skulls and postcranial skeletons. Hesperornis was a large, flightless diving bird that is known from Late Cretaceous rocks from the seaway that invaded central North America. The construction of its breastbone and shoulder shows that it evolved from a flying ancestor. Some specimens were over four feet long with strong hind limbs and lobed feet, and they used their teeth to capture swimming prey (Marsh 1880). Professor O. C. Marsh found the first remains of a bird (Hesperornis regalis) in the Smoky Hill Chalk of Trego County on July 25, 1871. The specimen (YPM 1200) was without a skull and Marsh had no way of knowing the full significance of his discovery. Marsh (1872) wrote, "One of the treasures secured during our explorations this year [1871] was the greater portion of the skeleton of a large fossil bird, at least five feet in height, which I was fortunate enough to discover in the Upper Cretaceous of Western Kansas. This interesting specimen, although a true bird --- as clearly as shown by the vertebræ and some other parts of the skeleton -- differs widely from any known recent or extinct forms of that class, and affords a fine example of a comprehensive type. The bones are all well preserved. The femur is very short, but the other portions of the legs are quite elongated. The metatarsal bones appear to have been separated. On my return, I shall fully describe this unique fossil under the name Hesperornis regalis." Hesperornis (“western bird”) had very large feet, diminutive wings and a flat unkeeled sternum, thus indicating that it could not fly. Its legs were turned backward so far they could only be used for swimming. Hesperornis had no need for wings or walking legs as long as it stayed in the water. There it lived like an oversized, flightless loon, skimming over the surface, diving, and swimming long distances while submerged. It could easily capture small fish while dodging carnivorous reptiles that might have fed upon it Hesperornis probably nested on isolated islands or it is possible that it gave birth to live young and never ventured onto dry land. Hills, L.V., Nicholls, E. L., Núñez-Betelu, M. and McIntyre, D.J. (1999) Hesperornis (Aves) from Ellesmere Island and palynological correlation of known Canadian localities. Can. J. Earth Sci./Rev. can. sci. Terre 36(9): 1583-1588 Abstract: A tarsometatarsus of Hesperornis from the Kanguk Formation on Ellesmere Island is described and illustrated and constitutes the northernmost occurrence of the genus. Palynological evidence and stratigraphic position indicate that Canadian occurrences of Hesperornis are Campanian in age except the specimen from the Mason River Formation which might be as young as early Maastrichtian. Paleogeographic reconstructions indicate that all specimens are from a seaway extending along the western interior of North America.
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