Hylonomus
Encyclopedia
Hylonomus was a very early reptile
. It lived 312 million years ago during the Late Carboniferous
period.
It is the earliest unquestionable reptile (Westlothiana
is older, but may in fact be an amphibian
, and Casineria
is rather fragmentary).
Hylonomus was 20 centimetres (7.9 in) long (including the tail) and probably would have looked rather similar to modern lizard
s. It had small sharp teeth and likely ate small invertebrates such as millipede
s or early insect
s.
Fossils of Hylonomus have been found in the remains of fossilized club moss stumps in Joggins, Nova Scotia
, Canada. It is supposed that, after harsh weather, the club mosses would crash down, with the stumps eventually rotting and hollowing out. Small animals such as Hylonomus, seeking shelter, would enter and become trapped, starving to death. Fossils of the basal pelycosaur
Archaeothyris
and the basal diapsid
Petrolacosaurus
are also found in the same region of Nova Scotia, although from a higher stratum, dated approximately 6 million years later.
Fossilized footprints found in New Brunswick
have been attributed to Hylonomus, at an estimated age of 315 million years.
This animal was discovered by John William Dawson
in the mid-19th century. The species name comes from Dawson's teacher, the geologist Sir Charles Lyell. While it has traditionally been included in the group Protothyrididae, later studies have shown that it is probably more closely related to diapsid
s.
Reptile
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...
. It lived 312 million years ago during the Late Carboniferous
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.
It is the earliest unquestionable reptile (Westlothiana
Westlothiana
Westlothiana lizziae was a reptile-like amphibian or possibly early reptile that bore a superficial resemblance to modern-day lizards. It lived during the Carboniferous period, about 350 million years ago. The type specimen was discovered in East Kirkton Quarry, Bathgate, Scotland, in 1984, and was...
is older, but may in fact be an amphibian
Amphibian
Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...
, and Casineria
Casineria
Casineria was a tetrapod which lived 340 million years ago in the Mississippian epoch. Casineria was a small animal with a total length estimated to have been 15 centimeters. It lived in what was then a fairly dry environment in Scotland. It is noted for its mix of primitive and advanced ...
is rather fragmentary).
Hylonomus was 20 centimetres (7.9 in) long (including the tail) and probably would have looked rather similar to modern lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s. It had small sharp teeth and likely ate small invertebrates such as millipede
Millipede
Millipedes are arthropods that have two pairs of legs per segment . Each segment that has two pairs of legs is a result of two single segments fused together as one...
s or early insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s.
Fossils of Hylonomus have been found in the remains of fossilized club moss stumps in Joggins, Nova Scotia
Joggins, Nova Scotia
Joggins is a Canadian rural community located in western Cumberland County, Nova Scotia. On July 7, 2008 a 15 km length of the coast constituting the Joggins Fossil Cliffs was officially inscribed on the World Heritage List.- History :...
, Canada. It is supposed that, after harsh weather, the club mosses would crash down, with the stumps eventually rotting and hollowing out. Small animals such as Hylonomus, seeking shelter, would enter and become trapped, starving to death. Fossils of the basal pelycosaur
Pelycosaur
The pelycosaurs are an informal grouping composed of basal or primitive Late Paleozoic synapsid amniotes. Some species were quite large and could grow up to 3 meters or more, although most species were much smaller...
Archaeothyris
Archaeothyris
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....
and the basal diapsid
Diapsid
Diapsids are a group of reptiles that developed two holes in each side of their skulls, about 300 million years ago during the late Carboniferous period. Living diapsids are extremely diverse, and include all crocodiles, lizards, snakes, and tuatara...
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....
are also found in the same region of Nova Scotia, although from a higher stratum, dated approximately 6 million years later.
Fossilized footprints found in New Brunswick
New Brunswick
New Brunswick is one of Canada's three Maritime provinces and is the only province in the federation that is constitutionally bilingual . The provincial capital is Fredericton and Saint John is the most populous city. Greater Moncton is the largest Census Metropolitan Area...
have been attributed to Hylonomus, at an estimated age of 315 million years.
This animal was discovered by John William Dawson
John William Dawson
Sir John William Dawson, CMG, FRS, FRSC , was a Canadian geologist and university administrator.- Life and work :...
in the mid-19th century. The species name comes from Dawson's teacher, the geologist Sir Charles Lyell. While it has traditionally been included in the group Protothyrididae, later studies have shown that it is probably more closely related to diapsid
Diapsid
Diapsids are a group of reptiles that developed two holes in each side of their skulls, about 300 million years ago during the late Carboniferous period. Living diapsids are extremely diverse, and include all crocodiles, lizards, snakes, and tuatara...
s.