[D] Baptornis advenus [~/~]
Describer
Marsh, 1877
Time
Cretaceous Late Santonian Campanian
Classification
Saurischia Theropoda Tetanurae Coelurosauria Maniraptora Avialae Ornithothoraces Ornithurae [Hesperonithiformes] [Baptornithidae]
Fossilsite
Niobrara Chalk Formation, Kansas, US
Info
Fragmentary skull, nearly complete postcranium
Baptornis advenus is distinguishable from Hesperornis by its smaller size and certain characters of the foot (Martin and Tate, 1976).
\\\"Included with UNSM 20030 [a specimen of the Late Cretaceous hesperornithid, Baptornis advenus from the upper Smoky Hill Chalk] are eight coprolites, two of which show small fish jaw and other bones. Most are round or elliptical in cross-section and are elongate, except for the two containing fish material. None shows spiral grooving or surface impressions.
George Sternberg, the collector, in a 1937 communication preserved in the records of the University of Nebraska State Museum [UNSM], makes the following reference to the association of these coprolites with Baptornis skeleton: \\\"There are 7 or 8 coprolites ... 2 show small fish bones. These are small compared to the other coprolites I have seen and were found mingled with the bones.\\\" It seems likely that these coprolites are correctly associated with the Baptornis skeleton; if so, they are the only ones known for a Cretaceous bird.
However, several of them fit together to for a long rounded structure that might be better interpreted as an intestinal cast. The jaw in one coprolite was identified by Orville W. Bonner of the University of Kansas (pers. comm., 1972) as Enchodus cf. parvus.\\\" (Martin and Tate, 1976)
Martin, L.D. & Bonner, O. (1977) An immature specimen of Baptornis advenus from the Cretaceous of Kansas. General Notes, University of Kansas Museum of Natural History and Department of Systematics and Ecology, Lawrence, Kansas 66045. Accepted 19 Aug. 76
In 1962 Bonner discovered a partial skeleton of the Cretaceous diving bird, Baptornis advenus, Kansas University Vertebrate Paleontology (KUVP) 16112, from the Smoky Hill (upper) member of the Niobrara Chalk. The specimen was in KUVP Logan County collecting locality 20, in the SE ¬, NW ¬, sec. 13, T 15 S, R 34 W, Logan County , Kansas . This is the same locality and horizon as the quarry that produced many slabs of the floating crinoid, Uintacrinus socialis (Miller et al. 1957).
The skeleton of Baptornis was fragmentary and from a young individual. Parts of the premaxilla, cervical, thoracic, and sacral vertebrae, pelvis, both femora, both tibiotarsi, both tarsometatarsi and some phalanges were recovered. Immature specimens of Mesozoic birds occur infrequently, although the proximal end of a tarsometatarsus associated with the type of B. advenus is also from a very young individual. The adult skelton of Baptornis has recently been described in detail by Martin and Tate (1976). In the present specimen, the fragment of premaxilla comes from a point just anterior to the external nares and indicates a bill similar to that of Hesperornis.
If teeth were present, they were restricted to the maxillary as in Hesperornis. The cervical vertebrae include specimens that seem to correspond to the 8th, 13th, and 14th cervicals of Hesperornis, but appear to be shorter and more massive than in that genus. The ventral border of the centrum corresponding to the 8th cervical is flat and hourglass shaped. The vertebrae corresponding to the 13th and 14th cervicals have very short centra and long sublateral processes, which do not unite ventrally.
Five vertebrae bearing rib facets are present. Two of these have narrow articulations of the centra and narrow hypapophyses. Another vertebra corresponds to the 22nd vertebra in Hesperornis and has small hypapophyses. The two following vertebrae are also preserved. That corresponding to the 24th in Hesperornis does not bear a rib. It has a short transverse process with a broad triangular area on its lateral margin for articulation with the ilium. A portion of the sacrum with three fused vertebrae is also present. Several of the dorsal vertebrae have small, shallow pits on the articular surface of the centrum although all are fully heterocoelous.
The right femur is represented by fragments of both the proximal and distal ends, while the left femur is represented by a portion of the proximal end including the head. The femur seems to have achieved most of the adult proportions. The tibiotarsi are represented by the distal end and part of the shaft of the right and the distal end of the left. The tarsals were not fused either to the tibia or to the metatarsals and therefore were not recovered.
The shaft of the tibiotarsus is very slender, flat and only about 72% as wide as that of an adult. This specimen was mistakenly identified as the proximal end of a large humerus by Walker (1967, p. 65). The three metatarsals are not fused in the proximal end of KUVP 16112, although the distal end was completely ossified. The metatarsals increase in size from the second to the fourth. The tarsometatarsus is at least 10% smaller th an that of an adult.
Proximal ends of two phalanges and the distal end of another are present. Descriptions of immature fossil birds are rare, although toward (1945) published a very useful paper on the growth stages of the tarsometatarsi of the fossil turkey Parapavo californicus, from Rancho La Brea. She recognized nine stages of development from newly hatched chicks to fully grown birds. The present specimens of Baptornis would seem to fall into her \\\"group IV\\\" which she characterized as having the \\\"distal end nearly completely formed except external foramen not entirely closed off. Proximal end still spongy\\\" (Howard 1945: 598).
The proximal end associated with the holotype of Baptornis advenus by Marsh (1880) would probably belong in Howard\\\'s \\\"group V\\\" where the proximal end is less porous and is flattened. It has a single small unfused tarsal which is roughly triangular in shape and is situated between metatarsals II and IV. A partial skeleton in the collections of the Field Museum of Natural History (FMNH 395) has the tibiotarsi with some of the sutures for the tarsals still visible. One large tarsal element covers the distal end.
The astragalus has not fused and has a long dorsal process. It is completely fused in the adult (Fig. 1, E) but the fusion appears to occur much later in the ontogeny of Baptornis than in modern birds The Hesperornithiformes are a primitive side branch of the early avian radiation that shares many characters with Archaeopteryx and theropod dinosaurs (Martin and Tate, 1976). However tte immature Baptornis material shows that the major features of the mesotarsal joint must have been fully established before the separation of the Hesperornithiformes from the main avian line.
The fusion of the tarsals near the time of the termination of growth was also established before this split. It seems certain that KUVP 16112 is from a young bird considerably smaller than an adult and lacking the development of many of the grooves and ossified articular surfaces which assist the functioning of the foot. One wonders if such a young bird would be likely to have traveled long distances away from shore or if the skeleton may be interpreted as evidence that Baptornis nested in the vicinity of the find. Over one-third of the known specimens of Baptornis advenus have been from immature birds while Hesperornis, which is known from many more specimens, has not produced any comparably young individuals.
This suggests that the young of Hesperornis did not venture so far out to sea as did those of Baptornis, or that Hesperornis nested in a different region. We are grateful to M. Jenkinson and M. A. Neuner for critically reading the anuscript. Special thanks are due to C. B. Schultz, University of Nebraska State Museum (UNSND, R. Zangerl, Field Museum (FMNH), and John Ostrom, Yale Peabody Museum (YPM) for the use of specimens in their care.
Martin and Tate (1976) noted a small pit lying directly anterior to the diapophysis in the trunk vertebrae of Baptornis advenus and this is also present in Judinornis nogontsavensis Nessov and Borkin, 1983. The flat ventral side of the body is another character which might also be apomorphic for the Baptornithidae and circular pits in the articular surfaces of the centra of the thoaric vertebrae are also found in Baptornis and Judinornis. (Kurochkin, 2000)
Marsh, 1877
Time
Cretaceous Late Santonian Campanian
Classification
Saurischia Theropoda Tetanurae Coelurosauria Maniraptora Avialae Ornithothoraces Ornithurae [Hesperonithiformes] [Baptornithidae]
Fossilsite
Niobrara Chalk Formation, Kansas, US
Info
Fragmentary skull, nearly complete postcranium
Baptornis advenus is distinguishable from Hesperornis by its smaller size and certain characters of the foot (Martin and Tate, 1976).
\\\"Included with UNSM 20030 [a specimen of the Late Cretaceous hesperornithid, Baptornis advenus from the upper Smoky Hill Chalk] are eight coprolites, two of which show small fish jaw and other bones. Most are round or elliptical in cross-section and are elongate, except for the two containing fish material. None shows spiral grooving or surface impressions.
George Sternberg, the collector, in a 1937 communication preserved in the records of the University of Nebraska State Museum [UNSM], makes the following reference to the association of these coprolites with Baptornis skeleton: \\\"There are 7 or 8 coprolites ... 2 show small fish bones. These are small compared to the other coprolites I have seen and were found mingled with the bones.\\\" It seems likely that these coprolites are correctly associated with the Baptornis skeleton; if so, they are the only ones known for a Cretaceous bird.
However, several of them fit together to for a long rounded structure that might be better interpreted as an intestinal cast. The jaw in one coprolite was identified by Orville W. Bonner of the University of Kansas (pers. comm., 1972) as Enchodus cf. parvus.\\\" (Martin and Tate, 1976)
Martin, L.D. & Bonner, O. (1977) An immature specimen of Baptornis advenus from the Cretaceous of Kansas. General Notes, University of Kansas Museum of Natural History and Department of Systematics and Ecology, Lawrence, Kansas 66045. Accepted 19 Aug. 76
In 1962 Bonner discovered a partial skeleton of the Cretaceous diving bird, Baptornis advenus, Kansas University Vertebrate Paleontology (KUVP) 16112, from the Smoky Hill (upper) member of the Niobrara Chalk. The specimen was in KUVP Logan County collecting locality 20, in the SE ¬, NW ¬, sec. 13, T 15 S, R 34 W, Logan County , Kansas . This is the same locality and horizon as the quarry that produced many slabs of the floating crinoid, Uintacrinus socialis (Miller et al. 1957).
The skeleton of Baptornis was fragmentary and from a young individual. Parts of the premaxilla, cervical, thoracic, and sacral vertebrae, pelvis, both femora, both tibiotarsi, both tarsometatarsi and some phalanges were recovered. Immature specimens of Mesozoic birds occur infrequently, although the proximal end of a tarsometatarsus associated with the type of B. advenus is also from a very young individual. The adult skelton of Baptornis has recently been described in detail by Martin and Tate (1976). In the present specimen, the fragment of premaxilla comes from a point just anterior to the external nares and indicates a bill similar to that of Hesperornis.
If teeth were present, they were restricted to the maxillary as in Hesperornis. The cervical vertebrae include specimens that seem to correspond to the 8th, 13th, and 14th cervicals of Hesperornis, but appear to be shorter and more massive than in that genus. The ventral border of the centrum corresponding to the 8th cervical is flat and hourglass shaped. The vertebrae corresponding to the 13th and 14th cervicals have very short centra and long sublateral processes, which do not unite ventrally.
Five vertebrae bearing rib facets are present. Two of these have narrow articulations of the centra and narrow hypapophyses. Another vertebra corresponds to the 22nd vertebra in Hesperornis and has small hypapophyses. The two following vertebrae are also preserved. That corresponding to the 24th in Hesperornis does not bear a rib. It has a short transverse process with a broad triangular area on its lateral margin for articulation with the ilium. A portion of the sacrum with three fused vertebrae is also present. Several of the dorsal vertebrae have small, shallow pits on the articular surface of the centrum although all are fully heterocoelous.
The right femur is represented by fragments of both the proximal and distal ends, while the left femur is represented by a portion of the proximal end including the head. The femur seems to have achieved most of the adult proportions. The tibiotarsi are represented by the distal end and part of the shaft of the right and the distal end of the left. The tarsals were not fused either to the tibia or to the metatarsals and therefore were not recovered.
The shaft of the tibiotarsus is very slender, flat and only about 72% as wide as that of an adult. This specimen was mistakenly identified as the proximal end of a large humerus by Walker (1967, p. 65). The three metatarsals are not fused in the proximal end of KUVP 16112, although the distal end was completely ossified. The metatarsals increase in size from the second to the fourth. The tarsometatarsus is at least 10% smaller th an that of an adult.
Proximal ends of two phalanges and the distal end of another are present. Descriptions of immature fossil birds are rare, although toward (1945) published a very useful paper on the growth stages of the tarsometatarsi of the fossil turkey Parapavo californicus, from Rancho La Brea. She recognized nine stages of development from newly hatched chicks to fully grown birds. The present specimens of Baptornis would seem to fall into her \\\"group IV\\\" which she characterized as having the \\\"distal end nearly completely formed except external foramen not entirely closed off. Proximal end still spongy\\\" (Howard 1945: 598).
The proximal end associated with the holotype of Baptornis advenus by Marsh (1880) would probably belong in Howard\\\'s \\\"group V\\\" where the proximal end is less porous and is flattened. It has a single small unfused tarsal which is roughly triangular in shape and is situated between metatarsals II and IV. A partial skeleton in the collections of the Field Museum of Natural History (FMNH 395) has the tibiotarsi with some of the sutures for the tarsals still visible. One large tarsal element covers the distal end.
The astragalus has not fused and has a long dorsal process. It is completely fused in the adult (Fig. 1, E) but the fusion appears to occur much later in the ontogeny of Baptornis than in modern birds The Hesperornithiformes are a primitive side branch of the early avian radiation that shares many characters with Archaeopteryx and theropod dinosaurs (Martin and Tate, 1976). However tte immature Baptornis material shows that the major features of the mesotarsal joint must have been fully established before the separation of the Hesperornithiformes from the main avian line.
The fusion of the tarsals near the time of the termination of growth was also established before this split. It seems certain that KUVP 16112 is from a young bird considerably smaller than an adult and lacking the development of many of the grooves and ossified articular surfaces which assist the functioning of the foot. One wonders if such a young bird would be likely to have traveled long distances away from shore or if the skeleton may be interpreted as evidence that Baptornis nested in the vicinity of the find. Over one-third of the known specimens of Baptornis advenus have been from immature birds while Hesperornis, which is known from many more specimens, has not produced any comparably young individuals.
This suggests that the young of Hesperornis did not venture so far out to sea as did those of Baptornis, or that Hesperornis nested in a different region. We are grateful to M. Jenkinson and M. A. Neuner for critically reading the anuscript. Special thanks are due to C. B. Schultz, University of Nebraska State Museum (UNSND, R. Zangerl, Field Museum (FMNH), and John Ostrom, Yale Peabody Museum (YPM) for the use of specimens in their care.
Martin and Tate (1976) noted a small pit lying directly anterior to the diapophysis in the trunk vertebrae of Baptornis advenus and this is also present in Judinornis nogontsavensis Nessov and Borkin, 1983. The flat ventral side of the body is another character which might also be apomorphic for the Baptornithidae and circular pits in the articular surfaces of the centra of the thoaric vertebrae are also found in Baptornis and Judinornis. (Kurochkin, 2000)