†H. regalis Marsh, 1872
†H. crassipes (Marsh, 1876)
†H. gracilis Marsh, 1876
†H. altus (Marsh, 1893)
†H. montana Schufeldt, 1915
†H. rossicus Nesov & Yarkov, 1993
†H. bairdi Martin & Lim, 2002
†H. chowi Martin & Lim, 2002
†H. macdonaldi Martin & Lim, 2002
†H. mengeli Martin & Lim, 2002
†H. lumgairi Aotsuka & Sato, 2016 (in press) 
Lestornis Marsh, 1876
Coniornis Marsh, 1893
Hargeria Lucas, 1903
Hesperornis (meaning "western bird") is a genus of penguin-like bird
that spanned the first half of the
Campanian age of the Late
Cretaceous period (83.5–78 mya). One of the lesser-known discoveries
of the paleontologist O. C. Marsh in the late 19th century Bone Wars,
it was an early find in the history of avian paleontology. Locations
Hesperornis fossils include the
Late Cretaceous marine limestones
Kansas and the marine shales from Canada. Nine species are
recognised, eight of which have been recovered from rocks in North
America and one from Russia.
3 Classification and Species
7 Further reading
8 External links
Life restoration by Nobu Tamura, 2011.
Hesperornis was a large bird, reaching up to 1.8 metres (5.9 ft)
in length. It had virtually no wings, and swam with its
powerful hind legs. Fossil evidence shows that the toes were probably
lobed, as in today's grebes, rather than webbed as in those of loons.
Like many other
Mesozoic birds such as Ichthyornis,
teeth as well as a beak, which were used to hold prey. In the
hesperornithiform lineage they were of a different arrangement than in
any other known bird (or in non-avian theropod dinosaurs), with the
teeth sitting in a longitudinal groove rather than in individual
sockets, in a notable case of convergent evolution with
mosasaurs. The teeth of
Hesperornis were present
along nearly the entire lower jaw (dentary) and the back of the upper
jaw (maxilla). The front portion of the upper jaw (premaxilla) and tip
of the lower jaw (predentary) lacked teeth and were probably covered
in a beak. Studies of the bone surface show that at least the tips of
the jaws supported a hard, keratinous beak similar to that found in
modern birds. The palate (mouth roof) contained small pits
that allowed the lower teeth to lock into place when the jaws were
closed. They also retained a dinosaur-like joint between
the lower jaw bones. It is believed that this allowed them to rotate
the back portion of the mandible independently of the front, thus
allowing the lower teeth to disengage.
Marsh's now-obsolete 1880 reconstruction of H. regalis.
Hesperornis specimen was discovered in 1871 by Othniel
Charles Marsh. Marsh was undertaking his second western expedition,
accompanied by ten students. The team headed to Kansas
where Marsh had dug before. Aside from finding more bones belonging to
the flying reptile Pteranodon, Marsh discovered the skeleton of a
"large fossil bird, at least five feet in height". The specimen was
large, wingless, and had strong legs—Marsh considered it a diving
species. Unfortunately, the specimen lacked a head. Marsh
named the find
Hesperornis regalis, or "regal western
Marsh headed back west with a smaller party the following year. In
western Kansas, one of Marsh's four students, Thomas H. Russell,
discovered a "nearly perfect skeleton" of Hesperornis.
This specimen had enough of its head intact that Marsh could see that
the creature's jaws had been lined with teeth. Marsh saw
important evolutionary implications of this find, along with Benjamin
Mudge's find of the toothed bird Ichthyornis. In an 1873
paper Marsh declared that "the fortunate discovery of these
interesting fossils does much to break down the old distinction
between Birds and Reptiles". Meanwhile, Marsh's
relationship with his rival
Edward Drinker Cope
Edward Drinker Cope soured further after
Cope accidentally received boxes of fossils, including the toothed
birds, that were meant for Marsh. Cope called the birds "simply
delightful", but Marsh replied with accusations Cope had stolen the
bones. By 1873 their friendship dissolved into open
hostility, helping to spark the Bone Wars. While Marsh would rarely go
into the field after 1873, the collectors he paid continued to send
him a stream of fossils. He eventually received parts of 50 specimens
of Hesperornis, which allowed him to make a much stronger
demonstration of an evolutionary link between reptiles and birds than
had been possible before.
Classification and Species
H. regalis specimen at the AMNH
Many species have been described in this genus, though some are known
from very few bones or even a single bone and cannot be properly
compared with the more plentiful (but also incomplete) remains of
other similar-sized taxa. In many cases, species have been separated
by provenance, having been found in strata of different ages or in
different locations, or by differences in size.
The first species to be described, the type species, is Hesperornis
regalis. H. regalis is also the best known species, and dozens of
specimens (from fragments to more complete skeletons) have been
recovered, all from the Smoky Hill Chalk Member of the Niobrara
Formation (dating to the early
Campanian age, between 90–60 million
years ago). It is the only species of
which a nearly complete skull is known.
Hesperornis crassipes was named in 1876 by Marsh, who initially
classified it in a different genus as Lestornis crassipes. H.
crassipes was larger than H. regalis, had five ribs as opposed to four
in the first species, and differed in aspects of the bone sculpturing
on the breastbone and lower leg. H. crassipes is known from the same
time and place as H. regalis. One incomplete skeleton is known,
including teeth and parts of the skull.
Left leg of H. gracilis
Marsh explicitly named his second species of
Hesperornis in 1876 for
an incomplete metatarsus recovered from the same layers of the
Niobrara chalk as H. regalis. He named this smaller species H.
gracilis, and it was subsequently involved in the rather confused
taxonomy of a specimen which would eventually form the basis of the
new genus and species
Parahesperornis alexi. The type specimen of P.
alexi was assumed to belong to the same specimen as that of H.
gracilis, so when Lucas (1903) decided that the former specimen
represented a distinct genus, he mistakenly used the later specimen to
anchor it, creating the name Hargeria gracilis. This mistake was
rectified by later authors, who sank Hargeria back into Hesperornis
and renamed the more distinctive specimen
Type specimen (a partial right tibia) of H. altus in several views
The first species recognized from outside the Niobrara chalk,
Hesperornis altus, lived about 78 million years ago in Montana, and is
known from a partial lower leg from the base of the freshwater Judith
River Formation (or, possibly, the top of the underlying, marine
Claggett Shale formation). While initially placed in the new genus
Coniornis by Marsh, this was due mostly to his belief that Hesperornis
existed only in Kansas, so any species from
Montana should be placed
in a different genus. Most later researchers disagreed with this, and
have placed Coniornis altus in the same genus as
Hesperornis as H.
altus. A second species from
Montana has also
been described from the Claggett Shale. H. montana was named by
Shufeldt in 1915, and while its known material (a single dorsal
vertebra) cannot be directly compared to H. altus, Shufeldt and others
have considered it distinct due to its apparently smaller
In 1993, the first
Hesperornis remains from outside of North America
were recognized as a new species by Nessov and Yarkov. They named
Hesperornis rossicus for a fragmentary skeleton from the early
Russia near Volgograd. Several other specimens from
contemporary deposits have since been referred to this species. At
about 1.4 metres (4.6 ft) long, H. rossicus was the largest
Hesperornis and among the largest hesperornithines,
slightly smaller than the large Canadian genus Canadaga.
Aside from its large size and different geographic location, H.
rossicus differs from other
Hesperornis in several features of the
lower leg and foot, including a highly flattened
In 2002, Martin and Lim formally recognized several new species for
remains that had previously been unstudied or referred without
consideration to previously named North American hesperornithines.
These include the very small H. mengeli and H. macdonaldi, the
slightly larger H. bairdi, and the very large H. chowi, all from the
Sharon Springs member of the
Pierre Shale Formation in South Dakota
and Alberta, 80.5 million years ago.
In addition, there are some unassigned remains, such as SGU 3442 Ve02
and LO 9067t and bones of an undetermined species from Tzimlyanskoe
Reservoir near Rostov. The former two bones are probably H. rossicus;
some remains assigned to that species in turn seem to belong to the
latter undetermined taxon.
H. regalis skeleton in swimming pose; note feet pointing sideways
Hesperornis was primarily marine, and lived in the waters of such
contemporary shallow shelf seas as the Western Interior Seaway, the
Turgai Strait, and the North Sea, which then
were subtropical to tropical waters, much warmer than today. However,
some of the youngest known specimens of
Hesperornis have been found in
inland freshwater deposits of the Foremost Formation, suggesting that
some species of
Hesperornis may have eventually moved, at least
partially, away from a primarily marine habitat. Additionally, the
species H. altus comes from the freshwater deposits at the base of the
Judith River Formation.
Tions and hip structure has borne out this comparison. In terms of
limb length, shape of the hip bones, and position of the hip socket,
Hesperornis is particularly similar to the common loon (Gavia immer),
probably exhibiting a very similar manner of locomotion on land and in
water. Like loons,
Hesperornis were probably excellent foot-propelled
divers, but ungainly on land. Like loons, the legs were
probably encased inside the body wall up to the ankle, causing the
feet to jut out to the sides near the tail. This would have prevented
them from bringing the legs underneath the body to stand, or under the
center of gravity to walk. Instead, they likely moved on land by
pushing themselves along on their bellies, like modern
Hesperornis grew fairly quickly and continuously to adulthood,
as is the case in modern birds, but not Enantiornithes.
Hesperornis leg bone uncovered in the 1960s was examined by David
Burnham, Bruce Rothschild et al. and was found to bear bite marks from
a young polycotylid plesiosaur (possibly a
something similar). The Hesperornis's bone, specifically the condyle,
shows signs of infection, indicating the bird survived the initial
attack and escaped the predator. The discovery was published in the
Cretaceous Research in 2016.
^ Keiichi Aotsuka; Tamaki Sato (2016). "Hesperornithiformes (Aves:
Ornithurae) from the Upper
Cretaceous Pierre Shale, Southern Manitoba,
Cretaceous Research. in press.
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^ a b Perrins, Christopher (1987) . Harrison, C.J.O. (ed.).
Birds: Their Lifes, Their Ways, Their World. Pleasantville, NY, US:
Reader's Digest Association, Inc. pp. 165–166.
^ Marsh, Othniel Charles (1880): Odontornithes, a Monograph on the
Extinct Toothed Birds of North America. Government Printing Office,
^ Gregory, Joseph T. (1952). "The Jaws of the
Ichthyornis and Hesperornis" (PDF). Condor. 54 (2): 73–88.
doi:10.2307/1364594. JSTOR 1364594.
^ Heironymus, T.L.; Witmer, L.M. (2010). "Homology and evolution of
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^ Elzanowski, A. (1991). "New observations on the skull of Hesperornis
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^ Thomson, 191.
^ Thomson, 193.
^ a b Holtz, Thomas R. Jr. (2011) Dinosaurs: The Most Complete,
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^ Charles Schuchert and Clara Mae LeVene, O.C. Marsh: Pioneer in
Paleontology, p. 427. New York: Arno Press, 1978. Later, Russell
assisted Marsh while attending medical school; he became a surgeon,
professor of Clinical Surgery in the Yale School of Medicine, and
Marsh's personal physician until Marsh's death in 1899. See
Proceedings of the Connecticut State Medical Society (Google eBook)
and Genealogical and Family History of the State of Connecticut: A
Record of the Achievements of Her People in the Making of a
Commonwealth and the Founding of a Nation. Editorial staff: William
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Talcott, Frederick Bostwick, Ezra Scollay Stearns. Volume I (of 4).
New York: Lewis Historical Publishing Company, 1911.
^ a b Wallace, 86.
^ Thomson, 226.
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^ Wallace, 132.
^ Carpenter, K. (2003). Harries, P. J (ed.). "Vertebrate
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Stratigraphic Paleontology. Topics in Geobiology. 21: 421–437.
doi:10.1007/978-1-4020-9053-0. ISBN 978-1-4020-1443-7.
^ Marsh, O.C. (1876). "Notice of new Odontornithes". The American
Journal of Science and Arts. 11: 509–511.
^ Bell, A.; Everhart, M.J. (2009). "A new specimen of Parahesperornis
(Aves: Hesperornithiformes) from the Smoky Hill Chalk (Early
Campanian) of Western Kansas". Transactions of the
Kansas Academy of
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^ Mortimer, Michael (2004): The
Theropod Database: Phylogeny of taxa
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^ Shufeldt, R.W. (1915). "Fossil birds in the Marsh Collection of Yale
University". Transactions of the Connecticut Academy of Arts and
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^ Martin, L.D. (1984). "A new hesperornithid and the relationships of
Mesozoic birds". Transactions of the
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^ Shufeldt, R.W. (1915). "The fossil remains of a species of
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^ Kurochkin, (2000). "
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^ Martin, L. and Lim, (2002). "New information on the
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^ a b Rees, Jan & Lindgren, Johan; Lindgren (2005). "Aquatic birds
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^ Hills, L. V.; Nicholls, E. L.; Núñez-Betelu, L. "Koldo" M.;
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^ Chinsamy A, Martin, Larry D. & Dobson, P.; Martin; Dobson
(1998). "Bone microstructure of the diving
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Thomson, Keith Stewart (2008). The Legacy of the Mastodon: The Golden
Age of Fossils in America. Yale University Press.
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Greed, and the Greatest Scientific Feud of the Gilded Age. Houghton
Mifflin Books. ISBN 0-618-08240-9.
Everhart, M.J. (2012): Oceans of Kansas:
Hesperornis regalis Marsh
1872 – Toothed marine birds of the
Late Cretaceous seas. Version of
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Wikimedia Commons has media related to Hesperornis.
Eastern Kentucky University: Closeup of
Hesperornis skull. Retrieved
savageancientseas.com: Forward view of H. regalis skeleton in diving
pose. Note relalistic position of legs and toe rotation. Retrieved
UC Davis: Moveable 3D rendering of patella (kneecap) of Hesperornis
sp.. Digitized from KUVP PU17193. Requires Java, IFC or 3DC plugin.