''Protoclepsydrops'' is an extinct genus of early
synapsid
Synapsids + (, 'arch') > () "having a fused arch"; synonymous with ''theropsids'' (Greek, "beast-face") are one of the two major groups of animals that evolved from basal amniotes, the other being the sauropsids, the group that includes reptil ...
s, found in
Joggins, Nova Scotia
Joggins is a rural community located in western Cumberland County, Nova Scotia, Canada. On July 7, 2008 a 15-km length of the coast constituting the Joggins Fossil Cliffs was officially inscribed on the World Heritage List.[synapsid
Synapsids + (, 'arch') > () "having a fused arch"; synonymous with ''theropsids'' (Greek, "beast-face") are one of the two major groups of animals that evolved from basal amniotes, the other being the sauropsids, the group that includes reptil ...]
''
Clepsydrops''.
Description
Like ''Archaeothyris'', ''Protoclepsydrops'' resembled a modern
lizard
Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...
in superficial appearance. However, ''Protoclepsydrops'' had primitive
vertebra
The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...
e with tiny neural processes typical of their
amniote
Amniotes are a clade of tetrapod vertebrates that comprises sauropsids (including all reptiles and birds, and extinct parareptiles and non-avian dinosaurs) and synapsids (including pelycosaurs and therapsids such as mammals). They are disti ...
ancestors
An ancestor, also known as a forefather, fore-elder or a forebear, is a parent or (recursively) the parent of an antecedent (i.e., a grandparent, great-grandparent, great-great-grandparent and so forth). ''Ancestor'' is "any person from whom ...
. ''Protoclepsydrops'' is known from a few vertebrae and some
humeri
The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a round ...
.
[Reisz, R., 1972]
Pelycosaurian reptiles from the middle Pennsylvanian of North America. Harvard University
Classification
Its skeletal remains indicate that it may have been more closely related to
synapsids
Synapsids + (, 'arch') > () "having a fused arch"; synonymous with ''theropsids'' (Greek, "beast-face") are one of the two major groups of animals that evolved from basal amniotes, the other being the Sauropsida, sauropsids, the group that inc ...
than to
sauropsids
Sauropsida ("lizard faces") is a clade of amniotes, broadly equivalent to the class Reptilia. Sauropsida is the sister taxon to Synapsida, the other clade of amniotes which includes mammals as its only modern representatives. Although early sy ...
, making it a possible stem-mammal. If so, it is the oldest
synapsid
Synapsids + (, 'arch') > () "having a fused arch"; synonymous with ''theropsids'' (Greek, "beast-face") are one of the two major groups of animals that evolved from basal amniotes, the other being the sauropsids, the group that includes reptil ...
known, though its status is unconfirmed because its remains are too fragmentary. ''Protoclepsydrops'' lived slightly earlier than ''
Archaeothyris
''Archaeothyris'' is an extinct genus of ophiacodontid synapsid that lived during the Late Carboniferous and is known from Nova Scotia. Dated to 306 million years ago, ''Archaeothyris'', along with a more poorly known synapsid called ''Echinerpe ...
''.
[Benton M.J. and Donoghue P.C.J. 2006. Palaeontological evidence to date the tree of life. ''Molecular biology and evolution''. 24(1): 26–53]
/ref>
See also
* List of pelycosaurs
This list of pelycosaurs is an attempt to create a comprehensive listing of all genera that have ever been included in the synapsida excluding therapsida and purely vernacular terms. The list includes all commonly accepted genera, but also genera t ...
* Evolution of mammals
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 l ...
* List of transitional fossils
This is a partial list of transitional fossils (fossil remains of groups that exhibit both "primitive" and derived traits). The fossils are listed in series, showing the transition from one group to another, representing significant steps in t ...
* Carboniferous tetrapods
Carboniferous tetrapods include amphibians and reptiles that lived during the Carboniferous Period. Though stem-tetrapods originated in the preceding Devonian, it was in the earliest Carboniferous that the first crown tetrapods appeared, with ful ...
* '' Clepsydrops''
References
External links
Ophiacodontids
Prehistoric synapsid genera
Carboniferous synapsids
Transitional fossils
Fossils of Canada
Fossil taxa described in 1964
Paleontology in Nova Scotia
Paleozoic life of Nova Scotia
Taxa named by Robert L. Carroll
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