- Baptornis
Taxobox
name = "Baptornis"
status = fossil
fossil_range =Late Cretaceous (Coniacian -Campanian )
regnum =Animal ia
phylum =Chordata
classis =Aves
subclassis =Hesperornithes
ordo =Hesperornithiformes
familia = Baptornithidae
familia_authority = AOU, 1910
genus = "Baptornis"
genus_authority = Marsh, 1877
subdivision_ranks = Species
subdivision =
*"B. advenus" (type)
Marsh, 1877
*"B. varneri"
Martin & Cordes-Person, 2007
synonyms ="Parascaniornis" Lambrecht, 1933"Baptornis" ("diving bird") is an extinct
genus of flightless aquaticbird from theLate Cretaceous , some 87-80 million years ago (roughly mid-Coniacian to mid-Campanian faunal stage s). The fossils of "Baptornis advenus", the type species, were discoved inKansas , which at its time was mostly covered by theNorth American Inland Sea , 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 firstfossil s of this bird in the 1870's. This was, alongside the "Archaeopteryx ", one of the firstMesozoic birds to become known to science.Anatomy
The 1 m (3 ft 4 in) long "Baptornis" had lost the ability to fly, possessing only
vestigial wing s. Unlike its larger relative "Hesperornis ", the manual bones were not fully reduced, and it seems to have retained a tiny, finger-like stub. Its legs were powerful and the feet were very large with long toes that could not rotate well, allowing the animal to swim and dive at considerable speed. Its foot, altogether, was rather similar to that of a largeloon which it also resembled in overall bulk.Thus the toes of "Baptornis" were probably webbed as in loons or
ducks , rather than lobed as ingrebes and "Hesperornis ": for birds with lobed toes, rotating the toes is necessary to reduce drag when pulling the foot forward for a new stroke. Still, no skin impressions have been found of webs or lobes, leaving the matter open to debate. What is known from fossil skin impression is that thetarsometatarsus was covered by larger scutes in front and smaller scales behind like in loons, rather than all-scaled as in grebes.Like other
Hesperornithes , "Baptornis" probably hadteeth in itsbeak which allowed it to grabfish and other slippery prey. The skull is still unknown, but some teeth of the right size and shape have been found in the same rocks as "Baptornis" bones, and these are likely to be from the bird rather than a non-aviantheropod dinosaur [Though with some very small theropods becoming known more recently, it cannot be ruled out of course.] . Itsneck was unusually long, further extending its reach.The
pygostyle was long, high and narrow. The tail thus probably waslateral ly compressed and served asrudder ; a similar adaptation though less extreme is found in today's loons.As its relatives, the bones of "Baptornis" were dense, much like in mammals. This helped the animal to dive by reducing its
buoyancy . It also made the bones fossilize better, making them more common than those of flying birds like "Ichthyornis " which, compared to other vertebrate bones, are rare as fossils.Ecology
More material evidence exists for the ecology of "B. advenus" than for any other member of the Hesperornithes, with the possible exception of "Hesperornis regalis", but still much is left to conjecture. The
loon -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'sdarter s, 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's mergansers.The waters which it inhabited were fairly shallow epicontinental 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 of juvenile specimens are known. These tend to be from the northern part of its range - today's
Canada andAlaska - though they have also been found inKansas . This suggests that the birds were migratory like somepenguin s are today, moving polewards in summer to breed. The Cretaceous had a much warmerclimate than today; the waters inhabited by "Baptornis" weresubtropical totemperate .The long neck also provided extra mobility necessary since its feet were probably webbed rather than lobed, and thus optimized towards speed rather than maneuvrability. With the dense bones, the animals probably swam half-submerged as darters and
cormorant s do. The wings played no major role in locomotion, but may have been helpful in changing depth and/or direction, similar to asubmarine 'sdiving planes or a fish'spectoral fin s. It is even possible that it gained some additional maneuvrability by the hand-stub, which despite being much reduced still could be moved independently at thewrist joint .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 to "Hesperornis" which almost certainly had to slide on its belly or
galumph 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 from "Baptornis": Specimen
UNSM 20030 was found associated with somecoprolite s. 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 ", possibly "E. parvus". "Baptornis" had powerfulgastric juice s and/or regurgiated most indigestible parts of its prey as a pellet like most living fish-eating birds do, because the "Enchodus" remains make up only a small fraction of the coprolites' mass, most of which was nondescriptfeces .ystematics
"Baptornis" was related to the bigger, better known "
Hesperornis ". 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 as "Archaeopteryx " or theEnantiornithes .As "Baptornis" was quite peculiar among the Hesperornithes, the family Baptornithidae has been established for it. Presently this is considered
monotypic by most. However, it was recently established [See Rees & Lindgren (2005).] that the supposed "Cretaceous flamingo" "Parascaniornis stenisoei" from the Late Cretaceous ofIvö Island inSweden was not a flamingo and neither, as suggested by others, a gaviiform (loon) nor a procellariiform, but in fact belongs with "Baptornis". As there is insufficient material for a proper comparison, it is not known whether it is also ajunior synonym of "B. advenus" or a second species.In 2004, it was announced that material of a second species were being prepared for description. It is about twice as massive as the "B. advenus". The bones had been found in the lower
Pierre Shale of SWSouth Dakota . [See Person (2004).] James Martin and Amanda Cordes-Person named this species "Baptornis varneri" in 2007.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 of "
Neogaeornis ". 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 .Footnotes
References
* (2007):
Oceans of Kansas : [http://www.oceansofkansas.com/hesper.html "Hesperornis regalis" Marsh 1872 - Toothed marine birds of the Late Cretaceous seas] . Version of 2006-DEC-12. Retrieved 2007-AUG-23.
* (2004): A New Species of Diving Bird, "Baptornis", from the Lower Pierre Shale (Upper Cretaceous) of Southwestern South Dakota. Paper 33-7, Rocky Mountain (56th Annual) and Cordilleran (100th Annual) Joint Meeting, May 3–5, 2004.
* (2005): Aquatic birds from the Upper Cretaceous (Lower Campanian) of Sweden and the biology and distribution of hesperornithiforms. "Palaeontology " 48(6): 1321–1329. doi|10.1111/j.1475-4983.2005.00507.x (HTML abstract)External links
* [http://www.ucmp.berkeley.edu/diapsids/birds/hespero/hespero.jpgMounted skeleton] . Lobed feet less likely, but plausible. Retrieved 2007-AUG-23.
* [http://www.oceansofkansas.com/Hesperornis/martin60.jpgReconstructed skeleton] . Retrieved 2007-AUG-23.
* [http://home.arcor.de/oliver.volland/Internet/UnserUnterricht/Dinoschule/DinosNG/Baptornis.jpgReconstruction in life] . Color is based on reasonable assumption ofcountershading . Retrieved 2007-AUG-23.
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