{{short description|Extinct turtle}} {{Automatic taxobox | fossil_range = Late Cretaceous<br>{{fossil range|84.9|70.6}} | image = Turtle skull fossil.jpg | image_caption = Skull, Royal Tyrrell Museum in Alberta, Canada | taxon = Nichollsemys | authority = Brinkman, 2006<ref>Brinkman, D. (2006), ''A primitive chelonioid turtle from the late Campanian of North America''</ref> | subdivision_ranks = Species | subdivision = * †''N. baieri'' {{small|(Brinkman, 2006)}} }}

'''''Nichollsemys''''' is a genus of extinct sea turtles. The only known species is '''''Nichollsemys baieri'''''.<ref>[http://www.gbif.org/species/4822421 Global Biodiversity Information Facility, 2019: Nichollsemys (Brinkman, Hart, Jamniczky & Colbert, 2006)]</ref>

== Taxonomy == thumb|left|Biostratigraphy and paleobiogeography of Late Cretaceous chelonioids of North America, with ''Nichollsemys'' (1) at upper left Fossils of the ''Nichollsemys'' from Alberta [Alberta]], Canada, were discovered in 1997 by Ron Baier<ref>{{cite web |last1=Rob |first1=Baier |title=Stories of discovery: life under the sea |url=https://albertashistoricplaces.com/2022/08/31/stories-of-discovery-life-under-the-sea/ |website=RETROactive Eploring Alberta's Past |date=31 August 2022 |publisher=Historic Resources Management Branch of Alberta Arts, Culture and Status of Women |access-date=11 May 2025}}</ref> while prospecting near Chin Lake. Baier, who grew up in southeastern Alberta, contacted the Royal Terrell Museum which then performed a CT scan and identified it as the skull of a marine turtle dating to the Cretaceous Period and the first of its kind found. The fossils have been described by Donald Brinkman who named it in 2006.<ref>[https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=83032 Fossilworks, 2013: Nichollsemys (Behrensmeyer, A. K., and Turner, A.)]</ref> The fossils found so far are all skulls.

The name of ''Nichollsemys'' is a tribute to Elizabeth Nicholls, a paleontologist from Canada who studied marine reptiles from the Triassic period. She had previously done work with Brinkman when they found the ichthyosaur genus ''Parvinatator''.<ref>[http://www.paleofile.com/Turtlelist/Nichollsemys.asp Paleofile: Nichollsemys]. Accessed 16 June 2020</ref> The species name of ''baieri'' is in honor of Baier, who found the first fossil.

== Evolution == {{Clade|style=font-size:85%;line-height:85% |label1=Panchelonioidea |1={{Clade |1=†''Toxochelys'' |2={{Clade |1=†Protostegidae |label2=Chelonioidea |2={{Clade |1=†''Corsochelys'' |2=Dermochelyidae |3={{Clade |1=†'''''Nichollsemys''''' |2={{Clade |1=†''Allopleuron'' |2={{Clade |1=Cheloniidae |2={{Clade |1=†''Argillochelys'' |2=†''Procolpochelys'' |3={{Clade |1=†''Eochelone'' |2=†''Puppigerus'' }} |4={{Clade |1=†''Ctenochelys'' |2=†''Peritresius'' |3=†''Cabindachelys'' }} }} }} }} }} }} }} }} }}

== Description ==

The full length of the ''Nichollsemys'' is unknown, but Brinkman made a chart of the length of some parts of the specimen. The length from the basioccipital to the premaxilla measures 11.4&nbsp;cm, the width of all the quadrates measures 9.8&nbsp;cm, the depth at level of the quadrates measures 7.1&nbsp;cm, the intraorbital width measures 2&nbsp;cm, and the length measures 3.6&nbsp;cm.<ref>[http://www.researchgate.net/figure/Measurements-of-the-skull-of-Nichollsemys-baieri-TMP-97991-TMP-2000551_tbl1_295284770 Brinkman, Donald B, et al.: "Measurements of the Skull of Nichollsemys Baieri." Research Gate, Sept. 2006]</ref> The cranium has many things in common with that of Toxochelys: for example, they both have a rostrum basisphenoidale shaped like a rod.

<gallery> File:Nichollsemys_Baieri_front_view.jpg | ''Nichollsemys Baieri'' front view Photo taken at Royal Tyrrell Museum (4 May 2025 Susan Gerbic)

File:Nichollsemys_Baieri_side_view.jpg | ''Nichollsemys Baieri'' side view Photo taken at Royal Tyrrell Museum (4 May 2025 Susan Gerbic)

File:Royal_Tyrrell_Museum_display_discussing_the_Nichollsemys_baieri_fossil.jpg | Display for ''Nichollsemys Baieri'' Photo taken at Royal Tyrrell Museum (4 May 2025 Susan Gerbic)

</gallery>

== References == {{Reflist}}

{{Cheloniidae}}

{{Taxonbar|from=Q96286664}}

Category:Prehistoric turtle genera Category:Prehistoric turtles of North America Category:Chelonioidea Category:Paleontology in Alberta