| Baptornis | |
|---|---|
 | |
| Illustration of a tarsometatarsus, 1880 | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | Avialae |
| Clade: | †Hesperornithes |
| Family: | †Baptornithidae AOU, 1910 |
| Genus: | †Baptornis Marsh, 1877 |
| Species: | †B. advenus |
| Binomial name | |
| †Baptornis advenus Marsh, 1877[1] | |
| Synonyms | |
ParascaniornisLambrecht, 1933 | |
Baptornis ("diving bird") is agenus offlightless,aquatic birds from theLate Cretaceous, some 87-80 million years ago (roughly mid-Coniacian to mid-Campanianfaunal stages). The fossils ofBaptornis advenus, the type species, were discovered inKansas, which at its time was mostly covered by theWestern Interior Seaway, a shallowshelf sea. It is now known to have also occurred in today'sSweden, where theTurgai Strait joined the ancientNorth Sea; possibly, it occurred in the entireHolarctic.
Othniel Charles Marsh discovered the firstfossils of this bird in the 1870s. This was, alongside theArchaeopteryx, one of the firstMesozoic birds to become known to science.
More material evidence exists for the ecology ofB. advenus than for any other member of the Hesperornithes, with the possible exception ofHesperornis regalis, but still much is left to conjecture. Theloon-sized bird was of middle size among its relatives and had a markedly elongated neck. Presumably, it thus behaved in a manner similar to today'sdarters, hunting smaller, more mobile prey than its larger relatives. Unlike a darter however, it could not spear its prey, but instead held it with its beak like today'smergansers.
The waters which it inhabited were fairly shallowepicontinental or shelf seas. Remains found far off the prehistoric shore suggest that it either ventured far out and/or that it bred on islands. A considerable number ofjuvenile specimens are known. These tend to be from the northern part of its range - today'sCanada andAlaska - though they have also been found inKansas. This suggests that the birds weremigratory like somepenguins are today, moving polewards in summer to breed. The Cretaceous had a much warmerclimate than today; the waters inhabited byBaptornis weresubtropical totemperate.
While it was excellently adapted to swimming and diving,Baptornis is thought to have been clumsy on land, pushing itself along the rocks with its feet rather than actually walking. The natural position of the lower legs was flush against the body, with the feet stretched out sideways and thus it would have been unable to move upright without toppling over. As opposed toHesperornis which almost certainly had to slide on its belly orgalumph like anearless seal,Baptornis's lower leg was not as firmly placed along the body sides. Thus, it would have found it more easy to place its feet under its body with the toes pointing forwards and might have managed small hops or even an awkward waddle, body held low to the ground.
The only certain record of Hesperornithes' food found so far comes fromBaptornis: SpecimenUNSM 20030 was found associated with somecoprolites. These are small round lumps - maybe a centimeter in diameter or so - and contain the remains of a small species of the sabre-toothed "herring"Enchodus, possiblyE. parvus.Baptornis had powerfulgastric juices and/or regurgitated most indigestible parts of its prey as apellet like most living fish-eating birds do, because theEnchodus remains make up only a small fraction of the coprolites' mass, most of which was nondescriptfeces.
Baptornis was related to the bigger, better knownHesperornis. Both belonged to theHesperornithes, a group of prehistoric birds which were uniquely adapted to diving and swimming, and had teeth. Otherwise, they were fairly similar to living birds rather than to moredinosaur-like forms such asArchaeopteryx or theEnantiornithes.
AsBaptornis was quite peculiar among the Hesperornithes, thefamilyBaptornithidae has been established for it. Presently this is consideredmonotypic by most. However, it was recently established[2] that the supposed "Cretaceous flamingo"Parascaniornis stensioi from the Late Cretaceous ofIvö Island inSweden was not a flamingo and neither, as suggested by others, agaviiform (loon) nor aprocellariiform, but in fact belongs withBaptornis. As there is insufficient material for a proper comparison, it is not known whether it is also ajunior synonym ofB. advenus or a second species.
In 2004, it was announced that material of a second species were being prepared for description. This specimen was about twice as massive as the type ofB. advenus. The bones had been found in the lowerPierre Shale of SWSouth Dakota.[3] James Martin and Amanda Cordes-Person named this speciesBaptornis varneri in 2007, but it was later reclassified as a species of the genusBrodavis and may not have been closely related toB. advenus.[4]
In addition, two other prehistoric diving birds of the Late Cretaceous are sometimes placed in the Baptornithidae:
Potamornis is in all probability a member of the Hesperornithes. However, it is unclear with which of these it is most closely allied; some place it in the Baptornithidae.
More interesting - or controversial - is the case ofNeogaeornis. This bird, whose remains were found inChile, might be a baptornithid also. Others consider it closely related to certain modern birds, either theGaviiformes, or theProcellariiformes.
In 2015, a species-level phylogenetic analysis found the following relationships among hesperornitheans.[5]
| Hesperornithes |
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