Name: Hesperornis
(Western bird).
Phonetic: Hess-per-or-niss.
Named By: Othniel Charles Marsh - 1872.
Synonyms: Conirnis, Hargeria, Lestornis.
Classification: Chordata, Aves, Hesperornithiformes,
Hesperornithidae.
Species: H. regalis (type), H. altus, H.
bairdi, H.
chowi, H. crassipes, H. gracilis, H. macdonaldi, H. mengeli, H.
montana, H. rossicus.
Type: Piscivore.
Size: Up to 1.8 meters long for the largest species.
Known locations: Canada, Russia, Sweden, USA.
Time period: Campanian of the Cretaceous.
Fossil representation: Numerous remains representing
multiple species.
Hesperornis
seems to have been a prehistoric cross between a penguin and grebe.
Although there were many flight capable birds during the Campanian,
Hesperornis seems to have become secondarily
flightless. This is
indicated by the greatly reduced wings that were little more than
stubs. However, although they were useless for flight, they would
greatly enhance the birds streamlining as it dived underwater.
When
underwater, Hesperornis
was probably a very graceful and agile swimmer, its feet pushing it
down under the water, while the long neck would easily allow
Hesperornis to pluck fish from their hiding places.
But because the
legs and feet were angled to provide maximum propulsion in the water,
Hesperornis would have been very cumbersome on the
land, perhaps only
being able to shuffle along.
The
beak of Hesperornis is
well adapted for catching fish, with sharp teeth running the length of
the lower jaw, and at the back of the upper. A good example of
convergent evolution is the fact that the teeth are not in sockets like
their dinosaur ancestors, but in a longitudinal groove that ran down
the beak. Although not related to Hesperornis, or
even birds in
general, this same tooth holding groove is also seen in the mosasaurs
that swam the Cretaceous seas. On a quick side note, Hesperornis were
occasional prey to mosasaurs, as evidenced by Hesperornis
fossils found
within what was once the gut of a Tylosaurus.
Another adaptation for
the beak of
Hesperornis are small holes in the palate that allow
the lower teeth to
slot into them when the beak is closed.
Although
the majority of
Hesperornis remains are known from seas such as the
Western Interior
Seaway, some have also come from freshwater deposits, possibly
following river systems as they searched for fish.
Further reading
- Preliminary description of Hesperornis regalis, with notices of four
other new species of Cretaceous birds - The American Journal of Science
and Arts, series 3 3(13-18):360-365 - Othniel Charles Marsh - 1872.
- On the Odontornithes, or birds with teeth. - American Journal of
Science 10:403-408 - Othniel Charles Marsh - 1875.
- Notice of new Odontornithes - The American Journal of Science and
Arts 11: 509–511. - Othniel Charles Marsh - 1876.
- A new Cretaceous bird allied to Hesperornis. - The American Journal
of Science and Arts, series 3 45(265):81-82 - Othniel Charles Marsh -
1893.
- The fossil remains of a species of Hesperornis found in Montana - The
Auk 32 (3): 290–294. - R. W. Shufeldt - 1915.
- A middle Campanian, nonmarine occurrence of the Cretaceous toothed
bird Hesperornis Marsh - Canadian Journal of Earth Sciences 11 (9):
1335–1338 - R. C. Fox - 1974.
- A new hesperornithid and the relationships of the Mesozoic birds -
Transactions of the Kansas Academy of Science 87(3/4):141-150 - L. D.
Martin - 1984.
- New observations on the skull of Hesperornis with reconstructions of
the bony palate and otic region - Postilla 207: 1–20. - A. Elzanowski -
1991.
- Gesperornisy v Rossii [Hesperornithiforms in Russia]. - Russian
Journal of Ornithology 2(1):37-54 - L. A. Nessov & A. A. Yarkov
- 1933.
- Bone microstructure of the diving Hesperornis and the volant
Ichthyornis from the Niobrara Chalk of western Kansas - Cretaceous
Research 19 (2): 225–235. - A. Chinsamy, L. D. Martin & P.
Dobson - 1998.
- Hesperornis (Aves) from Ellesmere Island and palynological
correlation of known Canadian localities - Canadian Journal of Earth
Sciences 36 (9): 1583–1588. - L. V. Hills, E. L. Nicholls, L.
Núñez-Betelu, M. Koldo D. J. & McIntyre - 1999.
- Aquatic birds from the Upper Cretaceous (Lower Campanian) of Sweden
and the biology and distribution of hesperornithiforms - Palaeontology
48 (6): 1321–1329 - Jan Rees & Johan Lindgren - 2005.
- Hind limb and pelvis proportions of Hesperornis regalis: A comparison
with extant diving birds - Journal of Vertebrate Paleontology 26 (3):
115A. - F. Reynaud - 2006.
- A new evolutionary lineage of diving birds from the Late Cretaceous
of North America and Asia - Palaeoworld 21 (1): 59–63. - Larry D.
Martin, Evgeny N. Kurochkin & Tim T. Tokaryk - 2012.