Odontornithes: a monograph on the extinct toothed birds of North America; with thirty-four plates and forty woodcuts,

Abstract

Along the eastern slope of the Rocky Mountains, and especially on the adjoining plains in Kansas and Colorado, there is a series of Cretaceous strata remarkably rich in vertebrate fossils. The deposits are all marine, and, away from the mountains, they lie nearly horizontal. They have suffered much from erosion, and are still wasting away, especially along the river valleys. These beds consist mainly of a fine yellow chalk and calcareous shale, both admirably adapted to preserve delicate specimens, and here have been found the extinct Birds which form the subject of the present memoir. The geological horizon of the known Odontornitlies is in the Middle Cretaceous, and corresponds to the strata named by the writer the " Pteranodon beds." The latter are included in subdivision number three, in Meek and Hayden's section. The accompanying fossils are Mosasauroid reptiles, which are very abundant ; Plesiosaurs, allied to Pliosaurus ; Pterodactyles, of the genus Pteranodon; and many Fishes. With these occur Rndistes, and occasionally Ammonites, Belemnites, and various other Cretaceous invertebrates.

A molecular mechanism for the origin of a key evolutionary innovation, the bird beak and palate, revealed by an integrative approach to major transitions in vertebrate history

“…Apparent pleiotropic effects of the FGF and WNT pathways on both the premaxillae and the palatines are also consistent with our analysis of data from μCT scans of the palate of Hesperornis , the first stem‐group bird with a completely transformed upper beak. In correlation with its modern beak (Marsh ), Hesperornis has a fully modern bird palatine (Fig. E, F).…”

Novel insights into early neuroanatomical evolution in penguins from the oldest described penguin brain endocast

“…). Marsh () illustrated the brain endocasts of Hesperornis and Ichthyornis and did not reconstruct the presence of a wulst. However, Ichthyornis material has been considered to be too fragmentary to reconstruct brain morphology accurately (Edinger, ; Clarke, ) and Hesperornithine endocasts have not yet been published.…”

The Completeness of the Fossil Record of Mesozoic Birds: Implications for Early Avian Evolution

“…The CCM2 produces low completeness estimates for these species (8.70% and 14.75% respectively) because almost all available bones are from the same skeletal region (the hindlimb) and several specimens duplicate the same element. Santonian bird species are also represented by collections of disarticulated bones; however, several of these species, such as Hesperornis regailis , H. crassipes , Parahesperornis alexi , Baptornis advenus and Ichthyornis dispar , are represented by very large collections of bones, covering a much wider range of body regions [89], [91]–[93], and thus many more phylogenetic characters can be scored for each species. This is reflected in a much higher mean CCM2 score for the Santonian.…”