extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...
ophthalmosaurid
Ophthalmosauridae is an extinct family of thunnosaur ichthyosaurs from the Middle Jurassic to the early Late Cretaceous (Bajocian - Cenomanian) worldwide. Almost all ichthyosaurs from the Middle Jurassic onwards belong to the family, until the ex ...
ichthyosaur
Ichthyosaurs (Ancient Greek for "fish lizard" – and ) are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia ('fish flippers' – a designation introduced by Sir Richard Owen in 1842, altho ...
s known from
Northwest Territories
The Northwest Territories (abbreviated ''NT'' or ''NWT''; french: Territoires du Nord-Ouest, formerly ''North-Western Territory'' and ''North-West Territories'' and namely shortened as ''Northwest Territory'') is a federal territory of Canada. ...
of
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tota ...
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...
''Maiaspondylus'' is known from the holotypeUALVP 45635, a disarticulated but nearly complete
skeleton
A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside ...
preserved in three dimensions and from the referred materials UALVP 45639, two articulated, partially preserved embryos and eight articulated vertebrae of an adult, UALVP 45640, 14 articulated vertebrae of a juvenile, UALVP 45640, 12 articulated vertebrae, UALVP 45642, a partial snout and left dentaries with teeth and UALVP 45643, a fragmentary snout. All specimens were collected at
Hay River Hay River may refer to:
Places
* Hay River, Northwest Territories
* Hay River, Wisconsin
Rivers
* Hay River (Wisconsin)
* Hay River (Canada), a river in Alberta and Northwest Territories, Canada
* Hay River, Northern Territory, Australia
* Hay R ...
from the
Loon River Formation
The Loon River Formation is a geologic formation in Northwest Territories. It preserves fossils dating back to the Cretaceous period.
See also
* List of fossiliferous stratigraphic units in Northwest Territories
This is a list of fossiliferous ...
Early Cretaceous
The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma.
Geology
Pro ...
, about 110 million years ago.
All ''Maiaspondylus'' specimens were originally referred to '' Platypterygius''. However, all recent cladistic analyses found that ''Maiaspondylus'' is a valid genus of ophthalmosaurid. Patrick S. Druckenmiller and Erin E. Maxwell (2010) found it to be most closely related to ''" Platypterygius" americanus'', which probably do not belong to the genus ''Platypterygius''.
Etymology
''Maiaspondylus'' was named by Erin E. Maxwell and Michael W. Caldwell in
2006
File:2006 Events Collage V1.png, From top left, clockwise: The 2006 Winter Olympics open in Turin; Twitter is founded and launched by Jack Dorsey; The Nintendo Wii is released; Montenegro 2006 Montenegrin independence referendum, votes to declare ...
and the type species is ''Maiaspondylus lindoei''. The generic name is derived from ''maia'' (μαία), Greek for "caring mother" and ''spondylos'' (σπόνδυλος), Greek for "vertebra". The generic name named in reference to the unique specimen, UALVP 45639, that composed of two embryos agglutinated to eight articulated vertebrae of an adult (within its body cavity), presumably the mother. Maxwell and Caldwell (2003) suggested that this specimen proves that ''Maiaspondylus'' was viviparous, giving live birth. These embryos are the geologically youngest and the physically smallest known ichthyosaur embryos. The
specific name Specific name may refer to:
* in Database management systems, a system-assigned name that is unique within a particular database
In taxonomy, either of these two meanings, each with its own set of rules:
* Specific name (botany), the two-part (bino ...
honors the Geology Museum of the University of Alberta technician Allan Lindoe for discovering, collecting and preparating the specimens.
A study on the anatomy and phylogenetic relationships of ''Maiaspondylus lindoei'', ''" Ophthalmosaurus" cantabrigiensis'' and ''" Platypterygius" ochevi'' was published by Zverkov & Grigoriev (2020), who transfer ''"O". cantabrigiensis'' to the genus ''Maiaspondylus'', and consider ''"P. ochevi'' to be a
junior synonym
The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently.
* In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linna ...
of ''M. cantabrigiensis''.
Phylogeny
The following cladogram shows a possible phylogenetic position of ''Maiaspondylus'' in Ophthalmosauridae according to the analysis performed by Zverkov and Jacobs (2020).
See also
*
List of ichthyosaurs
This list of ichthyosaurs is a comprehensive listing of all genera that have ever been included in the order Ichthyosauria or the parent clade Ichthyopterygia, excluding purely vernacular terms. The list includes all commonly accepted genera, but a ...
*
Timeline of ichthyosaur research
This timeline of ichthyosaur research is a chronological listing of events in the history of paleontology focused on the ichthyosauromorphs, a group of secondarily aquatic marine reptiles whose later members superficially resembled dolphins, shar ...