Hapalodectidae
Encyclopedia
Hapalodectidae is an extinct family of relatively small-bodied (1–8 kg) mesonychian placental mammal
s from the Paleocene
and Eocene
of North America
and Asia
. Hapalodectids differ from the larger and better-known mesonychids
in having teeth specialized for cutting (presumably meat), while the teeth of other mesonychids, such as Mesonyx
or Sinonyx
, are more specialized for crushing bones. Hapalodectids were once considered a subfamily of Mesonychidae
, but the discovery of a skull of Hapalodectes
hetangensis showed additional differences justifying placement in a distinct family. In particular, H. hetangensis has a postorbital bar closing the back of the orbit
, a feature lacking in mesonychids. The skeleton of hapalodectids is poorly known and of the post-cranial elements, only the humerus
has been described. The morphology of this bone indicates less specialization for terrestrial locomotion than in mesonychids.
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s from the Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
and Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
and Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
. Hapalodectids differ from the larger and better-known mesonychids
Mesonychidae
Mesonychidae is an extinct family of medium to large-sized omnivorous-carnivorous mammals closely related to artiodactyls which were endemic to North America and Eurasia during the Early Paleocene to Late Eocene living from 65—33.9 mya, existing for approximately .- Description :The mesonychids...
in having teeth specialized for cutting (presumably meat), while the teeth of other mesonychids, such as Mesonyx
Mesonyx
Mesonyx was a wolf-like mammal of the family Mesonychidae, the type family of the order Mesonychia , existing 51.8—51.7 Ma . It may have been ancestral to cetaceans....
or Sinonyx
Sinonyx
Sinonyx was a wolf-like ungulate Mesonychid mammal from the late Paleocene of China that lived about 56 million years ago. It was an early primitive form of mesonychid, which some experts regard as a distinctive group of carnivorous condylarths, which gave rise to artiodactyls. Sinonyx was...
, are more specialized for crushing bones. Hapalodectids were once considered a subfamily of Mesonychidae
Mesonychidae
Mesonychidae is an extinct family of medium to large-sized omnivorous-carnivorous mammals closely related to artiodactyls which were endemic to North America and Eurasia during the Early Paleocene to Late Eocene living from 65—33.9 mya, existing for approximately .- Description :The mesonychids...
, but the discovery of a skull of Hapalodectes
Hapalodectes
Hapalodectes was a genus of otter-like mesonychid from the Late Paleocene to Early Eocene some 55 million years ago. Although the first fossils were found in Eocene strata of Wyoming, the genus originated in Mongolia, as the oldest species is H...
hetangensis showed additional differences justifying placement in a distinct family. In particular, H. hetangensis has a postorbital bar closing the back of the orbit
Orbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...
, a feature lacking in mesonychids. The skeleton of hapalodectids is poorly known and of the post-cranial elements, only the humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
has been described. The morphology of this bone indicates less specialization for terrestrial locomotion than in mesonychids.
Species
Family Hapalodectidae- Genus HapalodectesHapalodectesHapalodectes was a genus of otter-like mesonychid from the Late Paleocene to Early Eocene some 55 million years ago. Although the first fossils were found in Eocene strata of Wyoming, the genus originated in Mongolia, as the oldest species is H...
- Hapalodectes anthracinus
- Hapalodectes hetangensis
- Hapalodectes dux
- Hapalodectes leptognathus
- Hapalodecte slovei
- Hapalodectes serus
- Genus HapalorestesHapalorestesHapalorestes lived during the early to middle Eocene and were the largest of the Hapalodectids. Their weight is estimated at 1 to 8 kilograms....
- Hapalorestes lovei
- Genus MetahapalodectesMetahapalodectesMetahapalodectes makhchinus is an extinct mesonychian hapalodectid. The species was named by Dashzeveg.-External links:**...
- Metahapalodectes makhchinus
- Genus LohoodonLohoodonLohoodon lived during the middle Eocene and was named by Chow et al. Lohoodon could be found throughout China and Pakistan.-External links:*...
- Lohoodon lushiensis
- Genus HonanodonHonanodonHonanodon was named by Chow and could be found throughout China and Pakistan.-Species:*Genus Honanodon**Honanodon chow**Honanodon hebetis**Honanodon lushiensis**Honanodon macrodontus-External links:**...
- Honanodon chow
- Honanodon hebetis
- Honanodon lushiensis
- Honanodon macrodontus