Apatornis is a genus of prehistoric birds endemic to North America during the late Cretaceous. It currently contains a single species, Apatornis celer, which lived around the Santonian-Campanian boundary, dated to about 83.5 million years ago. The remains of this species were found in the Smoky Hill Chalk of the Niobrara Formation in Kansas, United States. It is known from a single fossil specimen: a synsacrum, the fused series of vertebrae over the hips.
While the known fossil remains are very incomplete, enough has been found to reasonably estimate that the body length of this bird was between 7–8 inches (18–20 cm).[1]
The type specimen of A. celer, YPM 1451, was reportedly discovered by Othniel Charles Marsh in October 1872 at Butte Creek in Logan County, Kansas. This location is now recognized as falling between Marker Units 15 and 19 of the Smoky Hill Chalk geological formation. An additional, more complete specimen had also been referred to Apatornis celer by Marsh.[2] This more complete specimen had historically been the one used almost exclusively to form the basis of what was known about Apatornis. However, Julia Clarke noted in 2004 that because the second specimen did not preserve any of the same bones as the first, the two could not be scientifically compared. Clarke therefore reclassified the second specimen as its own genus and species, Iaceornis marshi.[3]
Classification
The traditional genus Apatornis has been defined as a clade, specifically as all species more closely related to the type specimen YPM 1451 than to either Ichthyornis or modern birds.[3]
Apatornis celer was recognized as a distinct species by Marsh (1873). Its type species was originally classified as Ichthyornis celer. A. celer was long allied with Ichthyornis, having been assigned to Ichthyornidae by Marsh (1873), to Odontotormae by Marsh (1880), and to Ichthyornithiformes by Sepkoski (2002). Apatornis differs from Ichthyornis primarily in that it had at least one additional rib attached to the hip vertebrae (sacrum), possibly more as the entire synsacrum was not preserved in the only known specimen. Apatornis also lacked the ossified tendons covering the top of the sacral region in Ichthyornis. In a 2004 paper, Julia Clarke noted that the few unique characteristics preserved in the A. celer specimen, rather than suggesting a close relationship with Ichthyornis as originally thought, actually suggest it is more closely related to modern birds, a hypothesis also supported by Hope in 2002.[3] In 2022, Benito and colleagues noted the variability in the sacral anatomy among known Ichthyornis specimens, and suggested that the validity of Apatornis should be re-evaluated.[4]
Its exact relationships are unresolved, mainly due to the paucity of fossil remains. Though it has sometimes been considered to be closely related to modern waterfowl (Anseriformes),[5] most researchers today consider it to be an early member of the clade Ornithurae.[3]
References
^Perrins, Christopher (1987) [1979]. Harrison, C.J.O. (ed.). Birds: Their Lifes, Their Ways, Their World. Reader's Digest Association, Inc. pp. 167–168. ISBN0895770652.
^O. C. Marsh. 1873. On a new sub-class of fossil birds (Odontornithes). American Journal of Science and Arts 5(2):161-162
^ abcdClarke, J.A. (2004). "Morphology, phylogenetic taxonomy, and systematics of Ichthyornis and Apatornis (Avialae: Ornithurae)." Bulletin of the American Museum of Natural History, 1-179.
^Benito, J.; Chen, A.; Wilson, L.E.; Bhullar, B-.A. S.; Burnham, D.; Field, D.J. (2022). "Forty new specimens of Ichthyornis provide unprecedented insight into the postcranial morphology of crownward stem group birds". PeerJ. 10: e13919. doi:10.7717/peerj.13919.
^Chiappe, L.M., & Dyke, G.J. (2002). "The Mesozoic radiation of birds." Annual Review of Ecology and Systematics, 91-124.
March 09, 2023
apatornis, genus, prehistoric, birds, endemic, north, america, during, late, cretaceous, currently, contains, single, species, celer, which, lived, around, santonian, campanian, boundary, dated, about, million, years, remains, this, species, were, found, smoky. Apatornis is a genus of prehistoric birds endemic to North America during the late Cretaceous It currently contains a single species Apatornis celer which lived around the Santonian Campanian boundary dated to about 83 5 million years ago The remains of this species were found in the Smoky Hill Chalk of the Niobrara Formation in Kansas United States It is known from a single fossil specimen a synsacrum the fused series of vertebrae over the hips ApatornisTemporal range Late Cretaceous 83 5 Ma PreꞒ Ꞓ O S D C P T J K Pg N Holotype of A celerScientific classificationKingdom AnimaliaPhylum ChordataClade DinosauriaClade SaurischiaClade TheropodaClade AvialaeClade OrnithuraeGenus ApatornisMarsh 1873bSpecies A celerBinomial name Apatornis celer Marsh 1873a SynonymsIchthyornis celer Marsh 1873aWhile the known fossil remains are very incomplete enough has been found to reasonably estimate that the body length of this bird was between 7 8 inches 18 20 cm 1 The type specimen of A celer YPM 1451 was reportedly discovered by Othniel Charles Marsh in October 1872 at Butte Creek in Logan County Kansas This location is now recognized as falling between Marker Units 15 and 19 of the Smoky Hill Chalk geological formation An additional more complete specimen had also been referred to Apatornis celer by Marsh 2 This more complete specimen had historically been the one used almost exclusively to form the basis of what was known about Apatornis However Julia Clarke noted in 2004 that because the second specimen did not preserve any of the same bones as the first the two could not be scientifically compared Clarke therefore reclassified the second specimen as its own genus and species Iaceornis marshi 3 Classification EditThe traditional genus Apatornis has been defined as a clade specifically as all species more closely related to the type specimen YPM 1451 than to either Ichthyornis or modern birds 3 Apatornis celer was recognized as a distinct species by Marsh 1873 Its type species was originally classified as Ichthyornis celer A celer was long allied with Ichthyornis having been assigned to Ichthyornidae by Marsh 1873 to Odontotormae by Marsh 1880 and to Ichthyornithiformes by Sepkoski 2002 Apatornis differs from Ichthyornis primarily in that it had at least one additional rib attached to the hip vertebrae sacrum possibly more as the entire synsacrum was not preserved in the only known specimen Apatornis also lacked the ossified tendons covering the top of the sacral region in Ichthyornis In a 2004 paper Julia Clarke noted that the few unique characteristics preserved in the A celer specimen rather than suggesting a close relationship with Ichthyornis as originally thought actually suggest it is more closely related to modern birds a hypothesis also supported by Hope in 2002 3 In 2022 Benito and colleagues noted the variability in the sacral anatomy among known Ichthyornis specimens and suggested that the validity of Apatornis should be re evaluated 4 Its exact relationships are unresolved mainly due to the paucity of fossil remains Though it has sometimes been considered to be closely related to modern waterfowl Anseriformes 5 most researchers today consider it to be an early member of the clade Ornithurae 3 References Edit Perrins Christopher 1987 1979 Harrison C J O ed Birds Their Lifes Their Ways Their World Reader s Digest Association Inc pp 167 168 ISBN 0895770652 O C Marsh 1873 On a new sub class of fossil birds Odontornithes American Journal of Science and Arts 5 2 161 162 a b c d Clarke J A 2004 Morphology phylogenetic taxonomy and systematics of Ichthyornis and Apatornis Avialae Ornithurae Bulletin of the American Museum of Natural History 1 179 Benito J Chen A Wilson L E Bhullar B A S Burnham D Field D J 2022 Forty new specimens of Ichthyornis provide unprecedented insight into the postcranial morphology of crownward stem group birds PeerJ 10 e13919 doi 10 7717 peerj 13919 Chiappe L M amp Dyke G J 2002 The Mesozoic radiation of birds Annual Review of Ecology and Systematics 91 124 Retrieved from https en wikipedia org w index php title Apatornis amp oldid 1136441623, wikipedia, wiki, book, books, library,
