Pseudorca yokoyamai: Difference between revisions
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{{Short description|Extinct species of dolphin}} |
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{{Italic title}} |
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{{speciesbox |
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|fossil_range = [[ |
|fossil_range = [[Pleistocene]] |
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|genus = Pseudorca |
|genus = Pseudorca |
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|species = yokoyamai |
|species = yokoyamai |
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|authority = Matsumoto, 1926 |
|authority = Matsumoto, 1926 |
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'''''Pseudorca yokoyamai''''' is an [[extinct]] species of [[oceanic dolphin]] from the [[Calabrian (stage)|Calabrian stage]] of the [[ |
'''''Pseudorca yokoyamai''''' is an [[extinct]] species of [[oceanic dolphin]] from the [[Calabrian (stage)|Calabrian stage]] of the [[Pleistocene]] of Japan, an extinct relative of the modern day [[false killer whale]] (''P. crassidens''). |
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==Discovery and taxonomy== |
==Discovery and taxonomy== |
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''Pseudorca yokoyamai'' was [[species description|described]] in 1926 by Matsumoto Hikoshichiro of the [[Tohoku Imperial University]]. The [[holotype specimen]] is represented by two teeth–probably the very last two in the back of the mouth–and a [[paratype]] specimen consists of the right [[ramus of the mandible]] with seven teeth, though four teeth are incomplete. The holotype was found in Hommoku, [[Yokohama]]–the [[species name]] honoring the place of its discovery–and the paratype in the [[Kazusa Province]] on the opposite side of [[Tokyo Bay]]. It may represent an [[transitional fossil|intermediary phase]] between the modern false killer whale and [[pilot whale]]s (''Globicephala'' spp.).<ref name=hikoshichiro/><ref>{{cite journal|first1=P. J.|last1=Stacey|first2=S.|last2=Leatherwood|first3=R. W.|last3=Baird|year=1994|title=''Pseudorca crassidens''|journal=Mammalian Species|number=456|pages=1–6|url=http://www.cascadiaresearch.org/oldsite/robin/FKWmamspec.pdf|doi=10.2307/3504208|jstor=3504208 }}</ref> |
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==Description== |
==Description== |
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The teeth of ''P. yokoyamai'' are largely conical, though bend backward, with a smooth [[tooth enamel|enamel]] coating. On the holotype, the second-to-last and last teeth measured respectively {{convert|47|and|50|mm|abbr=on}} in height. ''P. yokowamai'' had smaller, though a greater number of, teeth than the modern false killer whale.<ref name=hikoshichiro/> |
The teeth of ''P. yokoyamai'' are largely conical, though bend backward, with a smooth [[tooth enamel|enamel]] coating. On the holotype, the second-to-last and last teeth measured respectively {{convert|47|and|50|mm|abbr=on}} in height. ''P. yokowamai'' had smaller, though a greater number of, teeth than the modern false killer whale.<ref name=hikoshichiro/> |
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The paratype represents the last seven teeth in the jaw, and there were perhaps three or four more teeth in front of it. The diameter of the [[tooth crown]] at the [[gumline]] is {{convert|14|–|15|mm|abbr=on}}, and the series of seven teeth is {{convert|177|mm|abbr=on}} long.<ref name=hikoshichiro>{{cite journal|first=M.|last=Hikoshichiro|year=1926|title=On some fossil cetaceans of Japan|journal=Science |
The paratype represents the last seven teeth in the jaw, and there were perhaps three or four more teeth in front of it. The diameter of the [[tooth crown]] at the [[gumline]] is {{convert|14|–|15|mm|abbr=on}}, and the series of seven teeth is {{convert|177|mm|abbr=on}} long.<ref name=hikoshichiro>{{cite journal|first=M.|last=Hikoshichiro|year=1926|title=On some fossil cetaceans of Japan|journal=Science Reports of the Tohoku Imperial University|volume=10|pages=23–25}}</ref> |
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==References== |
==References== |
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{{Reflist}} |
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{{Taxonbar|from=Q56276531}} |
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[[Category:Oceanic dolphins]] |
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[[Category:Mammals described in 1926]] |
[[Category:Mammals described in 1926]] |
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Latest revision as of 20:18, 22 February 2023
| Pseudorca yokoyamai Temporal range: Pleistocene
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Infraorder: | Cetacea |
| Family: | Delphinidae |
| Genus: | Pseudorca |
| Species: | †P. yokoyamai
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| Binomial name | |
| †Pseudorca yokoyamai Matsumoto, 1926
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Pseudorca yokoyamai is an extinct species of oceanic dolphin from the Calabrian stage of the Pleistocene of Japan, an extinct relative of the modern day false killer whale (P. crassidens).
Discovery and taxonomy[edit]
Pseudorca yokoyamai was described in 1926 by Matsumoto Hikoshichiro of the Tohoku Imperial University. The holotype specimen is represented by two teeth–probably the very last two in the back of the mouth–and a paratype specimen consists of the right ramus of the mandible with seven teeth, though four teeth are incomplete. The holotype was found in Hommoku, Yokohama–the species name honoring the place of its discovery–and the paratype in the Kazusa Province on the opposite side of Tokyo Bay. It may represent an intermediary phase between the modern false killer whale and pilot whales (Globicephala spp.).[1][2]
Description[edit]
The teeth of P. yokoyamai are largely conical, though bend backward, with a smooth enamel coating. On the holotype, the second-to-last and last teeth measured respectively 47 and 50 mm (1.9 and 2.0 in) in height. P. yokowamai had smaller, though a greater number of, teeth than the modern false killer whale.[1]
The paratype represents the last seven teeth in the jaw, and there were perhaps three or four more teeth in front of it. The diameter of the tooth crown at the gumline is 14–15 mm (0.55–0.59 in), and the series of seven teeth is 177 mm (7.0 in) long.[1]
References[edit]
- ^ a b c Hikoshichiro, M. (1926). "On some fossil cetaceans of Japan". Science Reports of the Tohoku Imperial University. 10: 23–25.
- ^ Stacey, P. J.; Leatherwood, S.; Baird, R. W. (1994). "Pseudorca crassidens" (PDF). Mammalian Species (456): 1–6. doi:10.2307/3504208. JSTOR 3504208.