A new Miocene sirenian from Kutch, India
eocene; India; kachchh; mammalia; mammalia; miocene; Paleontology; Sirenia
We report a new Miocene sirenian from District Kutch, State of Gujarat, India: Domingia sodhae gen. et sp. nov. The new species is a dugongine dugongid with flattened tusk-like upper incisors. Like some other Miocene dugongids, Domningia is large and has complex, bilophodont molars and three-rooted premolars, which are strongly worn. The rostrum is downturned significantly, similar to modern dugongs, and indicative of a specialized feeding mode. Phylogenetically, it is closely related to Dioplotherium, Rytiodus, Corystosiren, and Bharatisiren. Among these, Domningia is most similar to Bharatisiren indica and Dioplotherium manigaulti, in that all three taxa retain multi-rooted premolars. Similar to Bharatisiren, the nasal process of the premaxilla is long. Bharatisiren and Domningia are part of a late Oligocene and early Miocene radiation of dugongines in South Asia.
Thewissen J G M; Bajpai S
Acta Palaeontologica Polonica
2009
2009-03
Journal Article
<a href="http://doi.org/10.4202/app.2009.0102" target="_blank" rel="noreferrer noopener">10.4202/app.2009.0102</a>
Additional Holotype Remains Of Ambulocetus Natans (cetacea, Ambulocetidae), And Their Implications For Locomotion In Early Whales
earliest cetaceans; Eocene; evolution; extant taxa; extinct; mammalia; morphology; origin; osteology; Paleontology; skeleton
Madar S I; Thewissen J G M; Hussain S T
Journal of Vertebrate Paleontology
2002
2002-07
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1671/0272-4634(2002)022%5B0405:ahroan%5D2.0.co;2" target="_blank" rel="noreferrer noopener">10.1671/0272-4634(2002)022%5B0405:ahroan%5D2.0.co;2</a>
Cranial anatomy of Pakicetidae (Cetacea, Mammalia)
artiodactyls; eocene; evolution; hearing; origin; pakistan; Paleontology; whales
The skulls and isolated tympanics are described for the earliest whales, pakicetids, from the H-GSP Locality 62 in the Ganda Kas area in Northern Pakistan. Currently three pakicetid genera are known: Pakicetus, Ichthyolestes, and Nalacetus. Ichthyolestes is smaller than the two other genera. Nalacetus and Pakicetus are similar in size, but morphologically different. Pakicetids have a nasal opening at the tip of the rostrum. Their palate retains an incisive foramen. This study reveals three characters of the cranial anatomy useful for systematic analyses. In pakicetids the orbits are orientated dorsally, and there is no supraorbital shield. The dorsal orientation of the orbits is diagnostic for the family, and the lack of supraorbital shield distinguishes pakicetids, ambulocetids, and remingtonocetids from the other Eocene archaeocetes. The intertemporal region of the pakicetid skull is very narrow, a feature that also occurs in many other Eocene cetaceans. The tympanic, which is the most abundant cranial bone (more than 30 specimens) in the pakicetid collections from H-GSP Locality 62, can be used to distinguish the species of pakicetids. In Ichthyolestes, the tympanic bulla is of the same absolute size as in Pakicetus, hence relatively larger, and the tympanic bulla of Nalacetus is larger than either of these. Morphologically, the tympanic bullae differ between the genera, and on the basis of these morphologies it is possible to recognize a fourth species of pakicetid at this locality.
Nummela S; Hussain S T; Thewissen J G M
Journal of Vertebrate Paleontology
2006
2006-09
Journal Article
<a href="http://doi.org/10.1671/0272-4634(2006)26%5B746:caopcm%5D2.0.co;2" target="_blank" rel="noreferrer noopener">10.1671/0272-4634(2006)26%5B746:caopcm%5D2.0.co;2</a>
Dental morphology of Remingtonocetidae (Cetacea, Mammalia)
eocene; Paleontology; whale
Thewissen J G M; Bajpai S
Journal of Paleontology
2001
2001-03
Journal Article
<a href="http://doi.org/10.1666/0022-3360(2001)075%3C0463:dmorcm%3E2.0.co;2" target="_blank" rel="noreferrer noopener">10.1666/0022-3360(2001)075%3C0463:dmorcm%3E2.0.co;2</a>
Early eocene snakes from Kutch, Western India, with a review of the palaeophiidae
Boidae; Colubroidea; eocene; evolution; India; Madtsoiidae; new species; palaeoenvironment; Palaeophiidae; Paleontology; reptilia; serpentes; Ypresian
The early Eocene of Panandhro Mine (northwestern India) has produced a rich snake fauna largely dominated by palaeophiids. Three families are present: Palaeophiidae, ?Madtsoiidae or Boidae, and an indeterminate family of Colubroidea. The Palaeophiidae include two species: Pterosphenus kutchensis n. sp., that shows peculiar features, and Pt. biswasi n. sp. They are the earliest representatives of the genus. Madtsoiidae or Boidae are represented by only two specimens that do not permit distinction between these two families. If these fossils belong to the Boidae, then they might be the earliest representatives of that family in Asia. The colubroid from this site ranks among the earliest Cenozoic representatives of the group. The possibility that it belongs to n the Colubridae cannot be excluded; if this is the case, it would be the earliest known colubrid. Nearly all specimens belong to Pterosphenus Lucas, 1899, that was a highly aquatic genus. It lived in shallow water, probably in marine environment close to the coasts and/or in freshwater.
Rage J C; Bajpai S; Thewissen J G M; Tiwari B N
Geodiversitas
2003
2003
Journal Article
n/a
FOSSIL EVIDENCE FOR THE ORIGIN OF AQUATIC LOCOMOTION IN ARCHAEOCETE WHALES
eocene; pakistan; Science & Technology - Other Topics
Recent members of the order Cetacea (whales, dolphins, and porpoises) move in the water by vertical tail beats and cannot locomote on land. Their hindlimbs are not visible externally and the bones are reduced to one or a few splints that commonly lack joints. However, cetaceans originated from four-legged land mammals that used their limbs for locomotion and were probably apt runners. Because there are no relatively complete limbs for archaic archaeocete cetaceans, it is not known how the transition in locomotory organs from land to water occurred. Recovery of a skeleton of an early fossil cetacean from the Kuldana Formation, Pakistan, documents transitional modes of locomotion, and allows hypotheses concerning swimming in early cetaceans to be tested. The fossil indicates that archaic whales swam by undulating their vertebral column, thus forcing their feet up and down in a way similar to modern otters. Their movements on land probably resembled those of sea lions to some degree, and involved protraction and retraction of the abducted limbs.
Thewissen J G M; Hussain S T; Arif M
Science
1994
1994-01
Journal Article
<a href="http://doi.org/10.1126/science.263.5144.210" target="_blank" rel="noreferrer noopener">10.1126/science.263.5144.210</a>
Gnathic And Postcranial Skeleton Of The Largest Known Arctocyonid 'condylarth' Arctocyon Mumak (mammalia, Procreodi) And Ecomorphological Diversity In Procreodi
adaptations; artiodactyla; eocene; locomotor behavior; morphology; origin; Paleontology; radiation; revision
Procreodi is an order of Paleocene and Eocene mammals thought to lie at the base of the radiation of the paraphyletic condylarths.' Taxa within the order have been linked to the origins of other condylarth groups, and of some living orders. Within the order, there are specializations indicative of a range of behaviors, and a considerable size range including some of the largest Paleocene mammals. Arctocyon mumak is the largest known arctocyonid. Several craniodental specimens from the Tiffanian of western North America and one partial skeleton, preserving parts of the fore- and hind limbs, pelvic and pectoral girdles, and some vertebrae, with associated teeth and other bony elements, are described here for the first time. Skeletal elements of A. mumak are larger than those of other species of Arctocyon and Anacodon, but are otherwise similar in overall morphology. Certain features of the tarsus, such as the large plantar tubercle on the navicular and the well-developed groove below the sustentaculum tali, are shared between A. mumak and Anacodon to the exclusion of Artcocyon and are suggestive of plantigrady and a degree of fossoriality. Univariate and multivariate statistical analyses of six ecomorphological ratios successfully distinguishes a taxonomically diverse group of 47 extant taxa with differing locomotor specializations. When calculated for Arctocyon mumak, these ratios support the view that this taxon was a terrestrial, possibly semi-fossorial taxon. Other taxa within Procreodi are recovered as more arboreal or more terrestrial. Significant ecological and morphological variation exists within this understudied group. SUPPLEMENTAL DATASupplemental materials are available for this article for free at www.tandfonline.com/UJVP
Gould F D H; Rose K D
Journal of Vertebrate Paleontology
2014
1905-07
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1080/02724634.2014.841707" target="_blank" rel="noreferrer noopener">10.1080/02724634.2014.841707</a>
Intervertebral and Epiphyseal Fusion in the Postnatal Ontogeny of Cetaceans and Terrestrial Mammals
baleen; Cetacea; Evolutionary Biology; Zoology; India; skeleton; morphology; artiodactyls; Eocene; whales; locomotor evolution; body length; Epiphyseal; fusion; Intervertebral; Vertebra; vertebral osteology
In this paper we studied three related aspects of the ontogeny of the vertebral centrum of cetaceans and terrestrial mammals in an evolutionary context. We determined patterns of ontogenetic fusion of the vertebral epiphyses in bowhead whale (Balaena mysticetus) and beluga whale (Delphinapterus leucas), comparing those to terrestrial mammals and Eocene cetaceans. We found that epiphyseal fusion is initiated in the neck and the sacral region of terrestrial mammals, while in recent aquatic mammals epiphyseal fusion is initiated in the neck and caudal regions, suggesting locomotor pattern and environment affect fusion pattern. We also studied bony fusion of the sacrum and evaluated criteria used to homologize cetacean vertebrae with the fused sacrum of terrestrial mammals. We found that the initial ossification of the vertebral pedicles in the fetus may be a reliable indicator of sacral homology inmodern cetaceans. Finally, we also studied fusion of the centra of cervical vertebrae in B. mysticetus and found that it is not completed until after sexual maturity, and after 20 years of age.
Moran M M; Bajpai S; George J C; Suydam R; Usip S; Thewissen J G M
Journal of Mammalian Evolution
2015
2015-03
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1007/s10914-014-9256-7" target="_blank" rel="noreferrer noopener">10.1007/s10914-014-9256-7</a>
Locomotor evolution in the earliest cetaceans: functional model, modern analogues, and paleontological evidence
aquatic locomotion; Biodiversity & Conservation; efficiency; Environmental Sciences & Ecology; eocene; Evolutionary Biology; origin; otters; Paleontology; power output
We discuss a model for the origin of cetacean swimming that is based on hydrodynamic and kinematic data of modern mammalian swimmers. The model suggests that modern otters (Mustelidae: Lutrinae) display several of the locomotor modes that early cetaceans used at different stages in the transition from land to water. We use mustelids and other amphibious mammals to analyze the morphology of the Eocene cetacean Ambulocetus natans, and we conclude that Ambulocetus may have locomoted by a combination of pelvic paddling and dorsoventral undulations of the tail, and that its locomotor mode in water resembled that of the modern otter Lutra most closely. We also suggest that cetacean locomotion may have resembled that of the freshwater otter Pteronura at a stage beyond Ambulocetus.
Thewissen J G M; Fish F E
Paleobiology
1997
1997
Journal Article
<a href="http://doi.org/10.1017/s0094837300019850" target="_blank" rel="noreferrer noopener">10.1017/s0094837300019850</a>
New Applications For Constrained Ordination: Reconstructing Feeding Behaviors In Fossil Remingtonocetinae (cetacea: Mammalia)
Archaeocetes; components; Constrained ordination; Eocene; eocene cetaceans; evolution; Feeding; india; Mastication; morphology; odontoceti; Reconstruction; regression; suction; transition; whales
Cooper L N; Hieronymus T L; Vinyard C J; Bajpai S; Thewissen J G M
Experimental Approaches to Understanding Fossil Organisms: Lessons from the Living
2014
1905-07
Book Chapter
n/a
Protocetid cetaceans (Mammalia) from the Eocene of India
Cetacea; India; hearing; Paleontology; morphology; origin; pakistan; Eocene; locomotor evolution; Mammalia; middle eocene; earliest cetaceans; ambulocetidae; early whales; kutch; New genus; New species
Protocetid cetaceans were first described from the Eocene of India in 1975, but many more specimens have been discovered since then and are described here. All specimens are from District Kutch in the State of Gujarat and were recovered in deposits approximately 42 million years old. Valid species described in the past include Indocetus ramani, Babiacetus indicus and B. mishrai. We here describe new material for Indocetus, including lower teeth and deciduous premolars. We also describe two new genera and species: Kharodacetus sahnii and Dhedacetus hyaeni. Kharodacetus is mostly based on a very well preserved rostrum and mandibles with teeth, and Dhedacetus is based on a partial skull with vertebral column. The Kutch protocetid fauna differs from the protocetid fauna of the Pakistani Sulaiman Range, possibly because the latter is partly older, and/or because it samples a different environment, being located on the trailing edge of the Indian Plate, directly exposed to the Indian Ocean.
Bajpai S; Thewissen J G M
Palaeontologia Electronica
2014
2014
Journal Article or Conference Abstract Publication
n/a
Skull of Megalohyrax eocaenus (Hyracoidea, Mammalia) from the Oligocene of Egypt
age; eocene; eutherian mammals; evolution; fayum; order; Paleontology; phylogeny; tree
The cranial anatomy of Megalohyrax eoceanus Andrews, 1903, a pliohyracid (Hyracoidea, Mammalia) from Oligocene levels of the Jebel Qatrani Formation of the Fayum Depression in Egypt, is described. Megalohyrax is the largest of the Fayum hyracoids, its skull is 391 mm long and the specimen described here is probably the best-preserved pliohyacid skull known. Megalohyrax has a strong lambdoid crest, a primitive alisphenoid canal, a notch for the minor palatine neurovascular group, orbits which are not anteriorly displaced, and a broad contact between the maxilla and frontal. In all of these features, Megalohyrax differs from modem hyracoids. Contrary to previous suggestions, the dental formula of Megalohyrax is 3.1.4.3, not similar to early sirenians (which have 5 premolars). Basioccipital morphology suggests that Megalohyrax may have had a eustachian sac.
Thewissen J G M; Simons E L
Journal of Vertebrate Paleontology
2001
2001-03
Journal Article
<a href="http://doi.org/10.1671/0272-4634(2001)021%5B0098:somehm%5D2.0.co;2" target="_blank" rel="noreferrer noopener">10.1671/0272-4634(2001)021%5B0098:somehm%5D2.0.co;2</a>
The Endocranial Cast of Indohyus (Artiodactyla, Raoellidae): The Origin of the Cetacean Brain
Eocene; Cetacea; Brain; CT scan; Endocast
We present the first description of the endocranial cast of the small raoellid artiodactyl Indohyus indirae. Raoellidae are sister group to Cetacea and the new morphological observations allow for outlining some of the early steps of the evolutionary history of the cetacean brain. The combination of primitive artiodactyl features and typical cetacean characters is unique about the Indohyus endocast. The fact that it presents the symplesiomorphic brain pattern observed in earliest Artiodactyla indicates that the cetacean brain derives from a very simple, plesiomorphic brain, with simple neocortical folding pattern, widely exposed midbrain, and concurrent small neocortex expansion. On the other hand, the Indohyus endocast shows characters that also occur in early cetaceans. These include modifications of the olfactory tract with narrow, elongated olfactory bulbs and peduncles, accompanied by a posterior location of the braincase in the cranium. The derived endocranial cast features of Indohyus mainly reflect changes in cranial architecture and these are most probably associated with modifications of the masticatory apparatus and a shift in diet. Indohyus meninges were very thin like in most terrestrial artiodactyls and it had no extensive rostral or lateral retia mirabilia. It however shows a branching pattern of ramification of intraosseous blood sinuses above the cerebellum that might represent the initial development of the caudal venous rete mirabile that would have colonized the endocranial cavity later on, in early archaeocetes.
Orliac MJ; Thewissen JGM
Journal Of Mammalian Evolution
2021
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
journalArticle
<a href="http://doi.org/10.1007/s10914-021-09552-x" target="_blank" rel="noreferrer noopener">10.1007/s10914-021-09552-x</a>
The origin and early evolution of whales: macroevolution documented on the Indian Subcontinent
Cetacea; India; evolution; energetics; Life Sciences & Biomedicine - Other Topics; artiodactyls; Eocene; pakistan; whales; cetaceans; Eocene; cetartiodactyla; locomotor evolution; dolphins; middle; semiaquatic mammals; underwater hearing
The origin of whales (order Cetacea) from a four-footed land animal is one of the best understood examples of macroevolutionary change. This evolutionary transition has been substantially elucidated by fossil finds from the Indian subcontinent in the past decade and a half. Here, we review the first steps of whale evolution, i.e. the transition from a land mammal to obligate marine predators, documented by the Eocene cetacean families of the Indian subcontinent: Pakicetidae, Ambulocetidae, Remingtonocetidae, Protocetidae, and Basilosauridae, as well as their artiodactyl sister group, the Raoellidae. We also discuss the influence that the excellent fossil record has on the study of the evolution of organ systems, in particular the locomotor and hearing systems.
Bajpai S; Thewissen J G M; Sahni A
Journal of Biosciences
2009
2009-11
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1007/s12038-009-0060-0" target="_blank" rel="noreferrer noopener">10.1007/s12038-009-0060-0</a>