Christine Marie Janis | |
|---|---|
 | |
| Alma mater | University of Cambridge 1973 Harvard University 1979 |
| Awards | George Gaylord Simpson Prize (1985) |
| Scientific career | |
| Institutions | University of Bristol current Brown University current Oregon State University University of Cambridge The Field Museum of Natural History The University of Chicago |
Christine Marie Janis is a British palaeontologist who specialises in mammals. She is currently based at the University of Bristol. [1]
Janis earned a bachelor's degree in Natural Sciences and Zoology from the University of Cambridge, and a PhD in Vertebrate Paleontology from Harvard University. [2] She has held positions as a researcher and lecturer at Oregon State University, Cambridge, the Field Museum of Natural History in the University of Chicago, the University of Bristol, and Brown University.
In 1985 Janis was awarded the George Gaylord Simpson Prize for Paleontology (Yale University, USA) and was elected Fellow of the Paleontological Society in 2007.
Janis attributes her interest in palaeontology to seeing Fantasia as a child. [2] She was married to fellow palaeontologist Jack Sepkoski (1948-1999).
Janis is best known for her contributions to the study of ungulates (hoofed mammals). As well as a large scientific publication list, Janis has contributed widely to textbooks and popular articles. [3]
Her earlier publications examine mammal teeth. For example, ungulate teeth changed from low crowned teeth to high crowned hypsodont teeth, as they evolved to adapt to a grassland diet, and this is correlated with changes in their digestion and can be used in their taxonomy. [4] [5] [6] She created the Hipsodonty Index, broadly used in mammal paleontology. [7] Her work on the evolution of horns in ungulates won her the Simpson Prize in 1985. [8]
In the 1990s, Janis switched focus from teeth to the biomechanics of locomotion. She has produced seminal works on the relationships between the lengths of limb bones in running mammals and their locomotion. [9] Latterly Janis has worked closely with her students and close colleagues to explore locomotion in various mammal groups, including camels, [10] various carnivores, [11] [12] and marsupials. [13] [14]
Among Janis's publications are the co-authored textbooks Evolution of Tertiary Mammals of North America. Vol. 2: Small Mammals, Edentates, and Marine Mammals and Vertebrate Life.
 | This section of a biography of a living person does not include any references or sources .(April 2020) |
Society of Vertebrate Paleontology (USA)
The Paleontological Society (USA)
The Palaeontological Association (UK)
GRIPS (Greater Rhode Island Paleontological Society) charter member.
Society for the Study of Mammalian Evolution (president)
Society for Integrative and Comparative Biology
National Center for Science Education
Ungulates are members of the diverse clade Euungulata, which primarily consists of large mammals with hooves. Once part of the clade "Ungulata" along with the clade Paenungulata, "Ungulata" has since been determined to be a polyphyletic and thereby invalid clade based on molecular data. As a result, true ungulates had since been reclassified to the newer clade Euungulata in 2001 within the clade Laurasiatheria while Paenungulata has been reclassified to a distant clade Afrotheria. Living ungulates are divided into two orders: Perissodactyla including equines, rhinoceroses, and tapirs; and Artiodactyla including cattle, antelope, pigs, giraffes, camels, sheep, deer, and hippopotamuses, among others. Cetaceans such as whales, dolphins, and porpoises are also classified as artiodactyls, although they do not have hooves. Most terrestrial ungulates use the hoofed tips of their toes to support their body weight while standing or moving. Two other orders of ungulates, Notoungulata and Litopterna, both native to South America, became extinct at the end of the Pleistocene, around 12,000 years ago.
Amphicyonidae is an extinct family of terrestrial carnivorans belonging to the suborder Caniformia. They first appeared in North America in the middle Eocene, spread to Europe by the late Eocene, and further spread to Asia and Africa by the early Miocene. They had largely disappeared worldwide by the late Miocene, with the latest recorded species at the end of the Miocene in Africa. They were among the first carnivorans to evolve large body size. Amphicyonids are colloquially referred to as "bear-dogs".
Thylacoleo is an extinct genus of carnivorous marsupials that lived in Australia from the late Pliocene to the Late Pleistocene, often known as marsupial lions. They were the largest and last members of the family Thylacoleonidae, occupying the position of apex predator within Australian ecosystems. The largest and last species, Thylacoleo carnifex, approached the weight of a lioness. The estimated average weight for the species ranges from 101 to 130 kg.
Creodonta is a former order of extinct carnivorous placental mammals that lived from the early Paleocene to the late Miocene epochs in North America, Europe, Asia and Africa. Originally thought to be a single group of animals ancestral to the modern Carnivora, this order is now usually considered a polyphyletic assemblage of two different groups, the oxyaenids and the hyaenodontids, not a natural group. Oxyaenids are first known from the Palaeocene of North America, while hyaenodonts hail from the Palaeocene of Africa.
Thylacosmilus is an extinct genus of saber-toothed metatherian mammals that inhabited South America from the Late Miocene to Pliocene epochs. Though Thylacosmilus looks similar to the "saber-toothed cats", it was not a felid, like the well-known North American Smilodon, but a sparassodont, a group closely related to marsupials, and only superficially resembled other saber-toothed mammals due to convergent evolution. A 2005 study found that the bite forces of Thylacosmilus and Smilodon were low, which indicates the killing-techniques of saber-toothed animals differed from those of extant species. Remains of Thylacosmilus have been found primarily in Catamarca, Entre Ríos, and La Pampa Provinces in northern Argentina.
Carnassials are paired upper and lower teeth modified in such a way as to allow enlarged and often self-sharpening edges to pass by each other in a shearing manner. This adaptation is found in carnivorans, where the carnassials are the modified fourth upper premolar and the first lower molar. These teeth are also referred to as sectorial teeth.
Thylacoleonidae is a family of extinct carnivorous diprotodontian marsupials from Australia, referred to as marsupial lions. The best known is Thylacoleo carnifex, also called the marsupial lion. The clade ranged from the Late Oligocene to the Late Pleistocene, with some earlier species the size of a possum, while the youngest members of the family belonging to the genus Thylacoleo reached sizes comparable to living big cats.
Arctocyon is an extinct genus of ungulate mammals. Arctocyon was a "ground dwelling omnivore", that lived from 61.3-56.8 Ma. Synonyms of Arctocyon include Claenodon, and Neoclaenodon. Arctocyon was likely plantigrade, meaning that it walked with its feet flat on the ground, rather than on its toes.
Miacoidea is a former paraphyletic superfamily of extinct placental mammals that lived during the Paleocene and Eocene epochs, about 66-33,9 million years ago. This group had been traditionally divided into two families of primitive carnivorous mammals: Miacidae and Viverravidae. These mammals were basal to order Carnivora, the crown-group within the Carnivoramorpha.
Carnivoramorpha is a clade of placental mammals of clade Pan-Carnivora from mirorder Ferae, that includes the modern order Carnivora and its extinct stem-relatives.
The evolution of mammals has passed through many stages since the first appearance of their synapsid ancestors in the Pennsylvanian sub-period of the late Carboniferous period. By the mid-Triassic, there were many synapsid species that looked like mammals. The lineage leading to today's mammals split up in the Jurassic; synapsids from this period include Dryolestes, more closely related to extant placentals and marsupials than to monotremes, as well as Ambondro, more closely related to monotremes. Later on, the eutherian and metatherian lineages separated; the metatherians are the animals more closely related to the marsupials, while the eutherians are those more closely related to the placentals. Since Juramaia, the earliest known eutherian, lived 160 million years ago in the Jurassic, this divergence must have occurred in the same period.
Didymictis is an extinct genus of placental mammals from extinct subfamily Didymictinae within extinct family Viverravidae, that lived in North America and Europe from the late Paleocene to middle Eocene.
Tillodontia is an extinct suborder of eutherian mammals known from the Early Paleocene to Late Eocene of China, the Late Paleocene to Middle Eocene of North America where they display their maximum species diversity, the Middle Eocene of Pakistan, and the Early Eocene of Europe. Leaving no descendants, they are most closely related to the pantodonts, another extinct group. The tillodonts were medium- to large-sized animals that probably fed on roots and tubers in temperate to subtropical habitats.
Dryolestidae is an extinct family of Mesozoic mammals, known from the Middle Jurassic to the Early Cretaceous of the North Hemisphere. The oldest known member, Anthracolestes, is known from the Middle Jurassic Itat Formation of Western Siberia, but most other representatives are known from the Late Jurassic of North America and the Late Jurassic and Early Cretaceous of Europe. Most members are only known from isolated teeth and jaw fragments. Like many other groups of early mammals, they are thought to have been insectivores. They are generally classified in Cladotheria, meaning that they are considered to be more closely related to marsupials and placentals than to monotremes. They are placed as part of the broader Dryolestida, which also includes the Paurodontidae, and also sometimes the South American-Antarctic Meridiolestida, which are often considered unrelated cladotherians. Dryolestidae taxon is not based on a phylogenetic definition, but instead on the possession of unequal roots for the molars of the lower jaw. Additionally, the clade is distinguished by hypsodonty in lower molars, and uneven labio-lingual height for the alveolar borders of the dentary.
Agriochoerus is an extinct genus of scansorial herbivore of the tylopod family Agriochoeridae, endemic to North America. Agriochoerus and other agriochoerids possessed claws, which is rare within Artiodactyla, as well as likely being scansorial. Agriochoerus was first described in 1869.
Thylacosmilidae is an extinct family of metatherian predators, related to the modern marsupials, which lived in South America between the Miocene and Pliocene epochs. Like other South American mammalian predators that lived prior to the Great American Biotic Interchange, these animals belonged to the order Sparassodonta, which occupied the ecological niche of many eutherian mammals of the order Carnivora from other continents. The family's most notable feature are the elongated, laterally flattened fangs, which is a remarkable evolutionary convergence with other saber-toothed mammals like Barbourofelis and Smilodon.
Alcidedorbignya is an extinct pantodont mammal known from the Early Paleocene Santa Lucia Formation at Tiupampa near Mizque, Cochabamba, Bolivia.
The grit, not grass hypothesis is an evolutionary hypothesis that explains the evolution of high-crowned teeth, particularly in New World mammals. The hypothesis is that the ingestion of gritty soil is the primary driver of hypsodont tooth development, not the silica-rich composition of grass, as was previously thought.
Protictis is an extinct paraphyletic genus of placental mammals from extinct subfamily Didymictinae within extinct family Viverravidae, that lived in North America from early Paleocene to middle Eocene.
Ectoganus is an extinct genus of taeniodonts from tribe Ectoganini within subfamily Stylinodontinae and family Stylinodontidae, that lived in North America from late Paleocene to early Eocene.
| International | |
|---|---|
| National | |
| Academics | |
| Other | |
