Ichthyornis

Ichthyornis
Kingdom	Animalia
Phylum	Chordata
Class	Aves
Order	Ichthyornithiformes
Family	Ichthyornithidae
Genus	Ichthyornis
Species	I. dispar
Synonyms	Graculavus anceps (Marsh, 1872) Colonosaurus mudgei Marsh, (1872)Graculavus agilis (Marsh, 1873)Ichthyornis victor (Marsh, 1876)Ichthyornis tener (Marsh, 1880)Ichthyornis validus )Marsh, 1880)Plegadornis antecessor (Wetmore, 1962)
Characters	Ichy

Ichthyornis is an early type of bird from the Cretaceous, 95-85 million years ago. This species lived in North America by the seashore and fed mainly on fish and scavenged meat. Unlike modern birds, Ichthyornis had teeth.

Description

It is thought that Ichthyornis was the Cretaceous ecological equivalent of modern seabirds such as gulls, petrels, and skimmers. It was the size of a dove, 9.4 in long, with a wingspan (not counting feathers) of around 17 in.

Ichthyornis is notable chiefly for its blend of vertebrae which are concave both in front and back (like some fish, which is where the bird gets its name) and more subtle features of its skeleton which set it apart from its close relatives. Ichthyornis may be most well known for its teeth. The teeth were present just in the middle portion of the upper and lower jaws. The jaw tips had no teeth and were covered in a beak. The beak of Ichthyornis, like the hesperornithids and other primitive birds, was made up of lots of distinct plates, like the beak of an albatross, not one sheet of keratin as in most birds. The teeth were more flattened than the round teeth found in crocodilians, though they got wider towards the base of the crown. The tips of the teeth were curved backward and lacked any serrations.

While the wings and breastbone were very modern in appearance (suggesting strong flight skills and placing it with modern birds in the advanced group Carinatae), the jaws had numerous small, sharp teeth. Unlike earlier birds such as the enantiornithines, it seems to have grown up in a short, continuous way.

History

Ichthyornis was first found in 1870 by Benjamin Franklin Mudge, a professor from Kansas State Agricultural College who recovered the fossils from the North Fork of the Solomon River in Kansas, USA. Mudge was a prolific fossil collector who shipped his findings to leading scientists for study. Mudge had previously had a close partnership with paleontologist Edward Drinker Cope of the Academy of Natural Sciences in Philadelphia. However, as described by S.W. Williston in 1898, Mudge was soon reached by Othniel Charles Marsh, Cope's foe in the so-called Bone Wars, a rush to find and name fossils in the American West. Marsh wrote to Mudge in 1872 and offered to name any important fossils free of charge, and to give Mudge sole credit for their findings. Marsh had been a friend of Mudge when they were young, so when Mudge learned of Marsh's request, he changed the address on the crate containing the Ichthyornis specimen (which had been meant for Cope and was ready to be sent), and shipped it to Marsh. Marsh had narrowly won the prestige of studying and naming the major fossil at the cost of his foe.

But, Marsh did not yet see the true importance of the fossil. Soon after finding it, he reported back to Mudge his view that the chalk slab held the bones of two distinct animals: a small bird, and the toothed jaws of some unknown reptile. Marsh found the rare vertebrae of the bird to look like those of a fish, so he named it Ichthyornis, or "fish bird." Later in 1872, Marsh described the toothed jaws as a new species of marine reptile, named Colonosaurus mudgei after their discoverer.

In 1873, Marsh had seen his error. Through the preparation and exposure of skull bones from the rock, he found that the toothed jaws must have come from the bird and not a sea reptile. Due to the special features of Ichthyornis (vertebrae concave on both side and teeth), Marsh chose to classify the bird in an whole new sub-class of birds he called the Odontornithes (or "toothed birds"), and in the new order Ichthyornithes (later Ichthyornithiformes). The only other bird Marsh included in these groups was the newly named Apatornis, which he had previously named as a species of Ichthyornis, I. celer. Mudge later noted the rare quality of these toothed birds (including Hesperornis, which was found to have teeth by 1877), and the irony of their association with the remains of toothless pterosaurs, flying reptiles which were just known to have had teeth in other parts of the world at that time.

Soon after these discoveries, Ichthyornis was known for its importance to the theory of evolution recently published by Charles Darwin. Darwin told Marsh in an 1880 letter that Ichthyornis and Hesperornis gave "the best support for the theory of evolution" since he had first wrote On the Origin of Species in 1859. (While Archaeopteryx was the first known Mesozoic bird and is now known to have had teeth too, the first specimen with a skull was not described until 1884). Others at the time also recognized the implications of a modern bird with reptilian teeth, and feared the dispute it caused. One Yale student described some men and women urging Marsh to hide Ichthyornis from the public since it lent too much support to evolutionary theory. Most accused Marsh of having tampered with the fossils or intentionally created a hoax by linking reptilian jaws with the body of a bird, claims that went on as late as 1967. But, an overwhelming majority of researchers have shown that Marsh's interpretation of the fossils was right, and he was fully claimed by later finds.

Mounted species

At the turn of the 20th Century, the Peabody Museum of Natural History at Yale University, where most Ichthyornis specimens were housed, began to place many of its most interesting or major fossils on display in the museum's Great Hall. Two panel mounts (that is, parts where the skeleton is arranged and set into a plaster slab) were made for Ichthyornis; one for I. dispar, and one for I. victor. Both were made by Hugh Gibb, who prepared most of Marsh's fossils for study and display. The I. dispar mount contained only the holotype fossils, while the I victor mount was a composite holding a range of different specimens to make the piece seem more complete ( but it did not hace any part of the actual I. victor specimen).

At some point before 1937, the specimen of I. victor type was re-assigned to the panel mount. Later reports of the specimen, even by the Peabody Museum's staff, mistakenly said that the original I. dispar sample made up most of the skeleton, when it was in fact just three bones. By 1997, the situation had grew so confused that Jacques Gauthier, the current curator of the museum's vertebrate paleontology collection, authorized the dismantling of both panel mounts. This let the bones be properly sorted out and studied in three dimensions, which had been impossible back when they were embedded in plaster. A full re-description of these species was published by paleontologist Julia Clarke in 2004.

Classification

Ichthyornis is close to the ancestry of modern birds, the Neornithes, but is from a separate line. It was long seen as related to some other Cretaceous taxa known from patchy remains — Ambiortus, Apatornis, Iaceornis and Guildavis — but these seem to be closer to the ancestors of modern birds than to Ichthyornis dispar. New data on the radiation of the latter, which is now known to have started as early as the Cretaceous, could shed more light on the exact relations of these taxa. In Clarke's 2004 review, the old order Ichthyornithiformes and the family Ichthyornithidae are now replaced by the subclass Ichthyornithes, which in the paper was also defined based on phylogenetic taxonomy as all descendants of the most recent common ancestor of Ichthyornis dispar and modern birds.

Of the several described species, only one, Ichthyornis dispar, is now recognized, following the seminal review by Julia Clarke. Marsh had previously named a copy now assigned to I. dispar as Graculavus anceps. Clarke argued that since the rules for naming animals state that a type species for a genus must have originally been placed in that genus, Ichthyornis anceps is ruled out to replace I. dispar as the type species and so must be seen as a junior synonym even though it was named first. But, Michael Mortimer pointed out that this is wrong; while I. anceps can not become the type species of Ichthyornis, it still can become the senior synonym of the type species I. dispar. Thus, I. ancesps should have been the right name for the only recognized Ichthyornis species.

There has been real confusion about the attribution of the fossil material. The similarity of the lower jaw and teeth to those of mosasaurs (fish-eating marine lizards) is so great that as late as 1952, it was claimed that it really belonged to a small species or young individual of or related to the genus Clidastes.

The presumed "Ichthyornis" lentus in fact comes from the early galliform genus Austinornis. "Ichthyornis" minusculus from the Bissekty Formation (Late Cretaceous) of Kyzyl Kum, Uzbekistan, is probably an enantiornithine.

Synonyms

Subclass-level

• Odontotormae Marsh, 1875

Genus-level

• Angelinornis Kashin 1972
• Colonosaurus Marsh, 1872c
• Plegadornis Wetmore, 1962 (non C.L. Brehm, 1855 - preoccupied)

Species-level

• Angelinornis antecessor (Wetmore, 1962)
• Colonosaurus mudgei Marsh, 1872c
• Graculavus agilis Marsh, 1873b
• Graculavus anceps Marsh, 1872a
• Ichthyornis antecessor (Wetmore, 1962) Olson, 1975
• Ichthyornis anceps (Marsh, 1872a) Marsh, 1880
• Ichthyornis agilis (Marsh, 1873b) Marsh, 1880
• Ichthyornis tener Marsh, 1880
• Ichthyornis validus Marsh, 1880
• Ichthyornis victor Marsh, 1876
• Plegadornis antecessor Wetmore, 1962

Ichthyornis in The Land Before Time

Ichy from the 4th movie is an Ichtyornis.

Ichy from the 4th movie

External links

• Ichthyornis dispar: A toothed, flying bird from the Late Cretaceous of Kansas by Mike Everhart, Oceans of Kansas website. Retrieved 2006-09-16.