Maiaspondylus

Maiaspondylus Temporal range: Early Cretaceous, 110 Ma PreЄ Є O S D C P T J K Pg N ↓
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	†Ichthyosauria
Family:	†Ophthalmosauridae
Genus:	†Maiaspondylus Maxwell & Caldwell, 2006
Species:	†M. lindoei
Binomial name
Maiaspondylus lindoei Maxwell & Caldwell, 2006

Maiaspondylus is an extinct genus of ophthalmosaurid ichthyosaur known from Northwest Territories of Canada.^[1]

Description

Maiaspondylus is known from the holotype UALVP 45635, a disarticulated but nearly complete skeleton 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 from the Loon River Formation, dating to the early Albian stage of the Early Cretaceous, about 110 million years ago.^[1]

All Maiaspondylus specimens were originally referred to Platypterygius. However, all recent cladistic analyses found that Maiaspondylus is a valid genus of ophthalmosaurid.^[2][3] Patrick S. Druckenmiller and Erin E. Maxwell (2010) found it to be most closely related to "Platypterygius" americanus, which probably don't belong to the genus Platypterygius.^[2]

Etymology

Maiaspondylus was named by Erin E. Maxwell and Michael W. Caldwell in 2006 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".^[1] 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.^[4] The specific name honors the Geology Museum of the University of Alberta technician Allan Lindoe for discovering, collecting and preparating the specimens.^[1]

References

1. ^ ^{a b c d} Erin E. Maxwell and Michael W. Caldwell (2006). "A new ichthyosaur from the Los Molles Formation (Early Bajocian), Neuquen Basin, Argentina". Journal of Paleontology 73 (4): 677–681. http://www.jstor.org/stable/1306766. 
2. ^ ^{a b} Patrick S. Druckenmiller and Erin E. Maxwell (2010). "A new Lower Cretaceous (lower Albian) ichthyosaur genus from the Clearwater Formation, Alberta, Canada". Canadian Journal of Earth Sciences 47 (8): 1037–1053. doi:10.1139/E10-028. http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=eng&journal=cjes&volume=47&year=0&issue=8&msno=e10-028. 
3. ^ Fischer, V.; Masure, E.; Arkhangelsky, M.S.; and Godefroit, P. (2011). "A new Barremian (Early Cretaceous) ichthyosaur from western Russia". Journal of Vertebrate Paleontology 31 (5): 1010–1025. doi:10.1080/02724634.2011.595464. http://www.tandfonline.com/doi/abs/10.1080/02724634.2011.595464. 
4. ^ Erin E. Maxwell and Michael W. Caldwell (2003). "First record of live birth in Cretaceous ichthyosaurs: closing an 80 million year gap". Proceedings of the Royal Society of London B 270 (1): S104-S107. doi:10.1098/rsbl.2003.0029. http://rspb.royalsocietypublishing.org/content/270/Suppl_1/S104.full.pdf. 

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