Ophiacodontidae
Ophiacodon mirus
- North America and Europe
The Ophiacodontidae are an affinity group of Pelycosaurier, a group of land vertebrates, which will be provided to synapsids. There were at least partially aquatic animals that fed on meat and possibly fish. The Ophiacodontidae family existed in the period before 311-273 million years ago.
- 2.1 Locations
Features
The main feature of Ophiacodontidae was their primary skull window in the temporal region ( temporal or pace Ralf St ) behind the eye socket.
Her skull was elongated in later representatives of the group he had formed huge and massive compared to the body. The skull base was relatively low-lying. The framing of the orbit was very high on the skull. The bones of the cranium were generally less adherent to each other than with other Eupelycosauria.
The pointed snout contained numerous (more than 40) uniform ( homodonte ) teeth, which were small and pointed and adapted for grasping prey. In a notch of the mandible sat a well-trained Mandibularfenster. Above the canine teeth on the upper jaw was an aspiring lead. The lacrimal bone was elongated. The postdorsalen processes of the premaxilla were elongated and thin, they were separated at the midline from the anterior projection of the nasal bone. The Angular had a well-developed ventral keel. The lower edge of the postorbital skull was concave in shape and enclosed the cheekbone. The Tabulare showed a large medial projection.
Shoulder and pelvic girdles were well developed, the fingers were flattened and served in some types of locomotion in water, the carpal-tarsal were also only slightly ossified.
Ophiacodontidae had a long tail. The vertebral bodies were shorter than in the Sphenacodontidae and Edaphosauridae.
The Ophiacodontidae varied considerably in size. While early representatives were only about 50 inches long, arrived late genera such Ophiacodon up to 4 meters in length.
Autapomorphies
The Ophiacodontidae were characterized by the following autapomorphies
- The antorbitale skull area was twice as long as the location behind the eye socket ( For other synapsids he is much shorter ).
- The nasal bone was longer than the frontal bone and almost twice as long as the parietal bone ( For other synapsids it is shorter).
- The paraoccipitale extension on the occiput was short and did not extend to the malar ( For other synapsids it is longer and reaches the square leg or the leg scales ).
- The Tabulare expanded in the ventral direction only until the supraoccipital from ( In other synapsids it reaches much further down ).
Occurrence and distribution
The earliest representatives of this group was Archaeothyris, which is also the oldest doubt one of the synapsids belonging animal. He lived in the Pennsylvanian ( " Upper Carboniferous ", turning Moscovian / Kasimovian ) before approximately 311-305 million years ago. Fossil evidence of this genus were found in the Morien Group in the Canadian province of Nova Scotia.
Also Clepsydrops was an early genus of Ophiacodontidae. The eponymous genus Ophiacodon is occupied with several species from the late Carboniferous and Permian.
In the Middle Permian ( Artinskian ) the Ophiacodontidae are extinct.
Locations
Fossils of these animals are so far mostly occupied only from North America, with the exception of Stereorhachis, which occurs only in Europe and Ophiacodon which may occur in Europe.
North America:
- Canada: Nova Scotia - Morien Group - Moscovian / Kasimovian
Europe:
- England - Kenilworth breccia - Cisuralium
Way of life
That the Ophiacodontidae were semi- aquatic fish -eater, is not accepted by all scientists ( see, eg, Reisz ).
System
The Ophiacodontidae, together with the Edaphosauridae and Sphenacodontia (which counted among other Dimetrodon ), a common taxon, which is characterized by several features in the structure of the skull. This taxon is further developed within the Pelycosaurier in contrast to the Caseidae or Varanopseidae. However, the oldest known Synapside, Archaeothyris is also assigned to the Ophiacodontidae. The exact lineages within these animals are therefore not yet been unequivocally ascertained.
According to Carroll ( 1988) the following genera are assigned to the Ophiacodontidae:
- Archaeothyris Reisz, 1972 ( Middle Pennsylvanian )
- Baldwinonus Romer & Price, 1940 ( Early Permian)
- Clepsydrops Cope 1875 (late Pennsylvanian )
- Ophiacodon Marsh 1878 ( late Pennsylvanian and early Permian)
- Protoclepsydrops (early Pennsylvanian ) - controversial. If accepted, this taxon would be the oldest known Synapside.
- Stereophallodon Romer 1937 (early Permian)
- Stereorhachis Gaudry 1880 ( late Pennsylvanian )
- Varanosaurus Broili 1904 ( early Permian) - controversial
Ophiacodon retro versus