Archaeothyris
Encyclopedia
Archaeothyris was a very early mammal-like reptile, which lived in the late Carboniferous
period. Dated to 306 million years ago, it is the oldest undisputed synapsid
known.
(Protoclepsydrops
is slightly older, but its status as a synapsid
is unclear as the remains are more fragmentary). It was found in Nova Scotia
, at the same locality as Hylonomus
, and Petrolacosaurus
, all of which resemble Archaeothyris.
, a group of early pelycosaurs that evolved early in the Late Carboniferous. It is thus seen as the precursor of all synapsids (which include mammal
s).
s. While its sharp teeth were all of the same shape, it did possess a pair of enlarged canines, suggesting that it was a carnivore.
Archaeothyris lived in what is now Nova Scotia
, about 306 million years ago in the Carboniferous Period (Pennsylvanian
).
Nova Scotia at this time was a swamp, similar to today's Everglades
in Florida
. The "trees" (actually giant club mosses) were very tall, some, such as Lepidodendron
, up to 50 metres (164 ft) tall. Archaeothyris and the other early amniotes dwelled on the forest ground.
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
period. Dated to 306 million years ago, it is the oldest undisputed synapsid
Synapsid
Synapsids are a group of animals that includes mammals and everything more closely related to mammals than to other living amniotes. They are easily separated from other amniotes by having an opening low in the skull roof behind each eye, leaving a bony arch beneath each, accounting for their name...
known.
(Protoclepsydrops
Protoclepsydrops
Protoclepsydrops was an early amniote, and its skeletal remains indicate that it may have been more closely related to synapsids than to sauropsids, making it a possible synapsid member. If so, it is the oldest synapsid known, though its status is unconfirmed because its remains were fragmentary....
is slightly older, but its status as a synapsid
Synapsid
Synapsids are a group of animals that includes mammals and everything more closely related to mammals than to other living amniotes. They are easily separated from other amniotes by having an opening low in the skull roof behind each eye, leaving a bony arch beneath each, accounting for their name...
is unclear as the remains are more fragmentary). It was found in Nova Scotia
Nova Scotia
Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...
, at the same locality as Hylonomus
Hylonomus
Hylonomus was a very early reptile. It lived 312 million years ago during the Late Carboniferous period.It is the earliest unquestionable reptile ....
, and Petrolacosaurus
Petrolacosaurus
Petrolacosaurus was a small, long, reptile, and the earliest diapsid known. It lived during the late Carboniferous period, the Joggins strata where it was found are dated to 302 million years old....
, all of which resemble Archaeothyris.
Systematics
Archaeothyris belonged to the family OphiacodontidaeOphiacodontidae
Ophiacodontidae were pelycosaur synapsids. They appeared in the late Carboniferous period. Archaeothyris, and Clepsydrops were among the earliest Ophiacodontids. Archaeothyris and its relatives were the members of this family. Some ophiacodonts were semi-aquatic, and few were fully aquatic, but...
, a group of early pelycosaurs that evolved early in the Late Carboniferous. It is thus seen as the precursor of all synapsids (which include mammal
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).
Appearance and lifestyle
Unlike Hylonomus and its kin, Archaeothyris was relatively large, measuring 50 centimetres (19.7 in) head to tail. It was also more advanced than the early sauropsids, having strong jaws that could open wider than those of the early reptileReptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
s. While its sharp teeth were all of the same shape, it did possess a pair of enlarged canines, suggesting that it was a carnivore.
Archaeothyris lived in what is now Nova Scotia
Nova Scotia
Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...
, about 306 million years ago in the Carboniferous Period (Pennsylvanian
Pennsylvanian
The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly . As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain...
).
Nova Scotia at this time was a swamp, similar to today's Everglades
Everglades
The Everglades are subtropical wetlands in the southern portion of the U.S. state of Florida, comprising the southern half of a large watershed. The system begins near Orlando with the Kissimmee River, which discharges into the vast but shallow Lake Okeechobee...
in Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
. The "trees" (actually giant club mosses) were very tall, some, such as Lepidodendron
Lepidodendron
Lepidodendron is an extinct genus of primitive, vascular, arborescent plant related to the Lycopsids . It was part of the coal forest flora. They sometimes reached heights of over , and the trunks were often over in diameter, and thrived during the Carboniferous period...
, up to 50 metres (164 ft) tall. Archaeothyris and the other early amniotes dwelled on the forest ground.
See also
- List of synapsids
- Evolution of mammalsEvolution of mammals__FORCETOC__The evolution of mammals within the synapsid lineage was a gradual process that took approximately 70 million years, beginning in the mid-Permian. By the mid-Triassic, there were many species that looked like mammals, and the first true mammals appeared in the early Jurassic...
- List of transitional fossils
- Carboniferous tetrapodsCarboniferous tetrapodsCarboniferous Tetrapods include amphibians and reptiles that lived during the Carboniferous Period.During this time, amphibians were the predominant tetrapods, and included the Temnospondyli, Lepospondyli, and Reptiliomorpha/Batrachosauria...
External links
- Transitional Vertebrate Fossils - includes description of important transitional genera from reptile to mammal (includes a little information about Archaeothyris)