# Lagrivea

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Lagrivea
> Markdown URL: https://mediated.wiki/source/Lagrivea.md
> Source: https://en.wikipedia.org/wiki/Lagrivea
> Source revision: 1284321251
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

{{short description|Extinct genus of squirrels}}
{{Speciesbox
| fossil_range = [Middle Miocene](/source/Middle_Miocene) (MN 7/8)
| genus = Lagrivea
| parent_authority = [Mein](/source/Pierre_Mein) and [Ginsburg](/source/L%C3%A9onard_Ginsburg), 2002
| species = vireti
| authority = Mein and Ginsburg, 2002
}}

'''''Lagrivea''''' is a fossil [genus](/source/genus) of [squirrel](/source/squirrel) from the [Middle Miocene](/source/Middle_Miocene) of [France](/source/France). The single species, '''''L. vireti''''', is known from three [mandible](/source/mandible)s (lower jaws) and two isolated teeth. All come from the fissure filling (a fossil deposit formed when a rock fissure filled with sediment) of La Grive L5, part of the [La Grive-Saint-Alban](/source/La_Grive-Saint-Alban) complex in [Saint-Alban-de-Roche](/source/Saint-Alban-de-Roche), southeastern France. ''Lagrivea'' was a large [tree squirrel](/source/tree_squirrel) with flat lower [incisor](/source/incisor)s and a large, triangular fourth lower [premolar](/source/premolar) (p4). Each of the four [cheekteeth](/source/cheekteeth) (p4 and three [molar](/source/molar_(tooth))s, m1 through m3) bears a deep basin in the middle of the crown. The m3 is about rectangular in shape, but rounded at the back. Although m1 and m2 have two roots, m3 has three.

==Taxonomy==
[Pierre Mein](/source/Pierre_Mein) and [Léonard Ginsburg](/source/L%C3%A9onard_Ginsburg) described ''Lagrivea vireti'' in 2002 in a review of the ages and faunas of the Miocene fossil sites of La Grive-Saint-Alban in southeastern France.<ref name=MG29>Mein and Ginsburg, 2002, p. 29</ref> They suggested that it was probably a [tree squirrel](/source/tree_squirrel) and related to the [Sciurini](/source/Sciurini).<ref name=MG30>Mein and Ginsburg, 2002, p. 30</ref> ''Lagrivea'' belongs to the squirrel family (Sciuridae), which first appears in the [Late Eocene](/source/Late_Eocene) of North America and [Early Oligocene](/source/Early_Oligocene) of Europe.<ref>McKenna and Bell, 1997, p. 121</ref> The [specific name](/source/specific_name_(zoology)), ''vireti'', honors [Jean Viret](/source/Jean_Viret) for his work on the mammals of La Grive-Saint-Alban.<ref name=MG29/>

==Description==
{| class="wikitable" align="right" style="margin-top: 0em; margin-left: 0.5em"
|+ Measurements<ref name=MG29/>
|-
! Variable !! Measurements (in mm)
|-
| Depth of mandible at m1 || 8.5, 8.7, 9.2
|-
| [Diastema](/source/Diastema_(dentistry)) between incisors and p4 || 6.1, 6.9, 7.6
|-
| p4–m3 || 11.1, 12.2, 12.2
|-
| Length of p4 || 2.37, 2.42
|-
| Width of p4 || 2.45, 2.45
|-
| Length of m1 || 2.55, 2.60, 2.66
|-
| Width of m1 || 2.68, 2.70, 2.75
|-
| Length of m2 || 2.8, 3.03, 3.07
|-
| Width of m2 ||  2.90, 3.05, 3.18
|-
| Length of m3 || 3.22
|-
| Width of m3 || 2.75
|}
''Lagrivea'' is known from three mandibles (lower jaws)—one, the [holotype](/source/holotype), with the fourth premolar (p4) and all three molars (m1–3) preserved; one with the incisor and m2; and one with the incisor, p4, m1, and m2—an isolated lower incisor, and an isolated m2. It was large for a squirrel,<ref name=MG29/> and can be distinguished from the fossil squirrels ''[Palaeosciurus](/source/Palaeosciurus)'', ''[Aliveria](/source/Aliveria)'', and ''[Ratufa obtusidens](/source/Ratufa_obtusidens)'' by its larger size.<ref name=MG30/>

In the mandible, the [diastema](/source/diastema_(dentistry)) (gap) between the incisors and the cheekteeth (premolars and molars) is relatively deep. The [mental foramen](/source/mental_foramen) (an opening in the bone) is located relatively high and before the p4. The upper and lower masseteric ridges, which are located on the outer side of the jaw and anchor some of the chewing muscles, meet at the m1. The surfaces of the incisor are very flat, but there are small, irregular striations in the [enamel](/source/tooth_enamel) along the length of the tooth.<ref name=MG29/>

The cheekteeth increase regularly in size from front to back.<ref name=MG29/> They all consist of a large central basin surrounded by [cusp](/source/cusp_(dentistry))s and crests.<ref>Mein and Ginsburg, 2002, fig. 43</ref> The basins are deeper than in ''Palaeosciurus'' and ''Ratufa obtusidens'' and lack crenulations in the enamel, which distinguishes them from another fossil squirrel, ''[Albanensia](/source/Albanensia)''.<ref name=MG30/> The first cheekteeth, p4, is large and about triangular in form, short and quite broad at the back.<ref>Mein and Ginsburg, 2002, pp. 29–30</ref> The two cusps at the front, the [protoconid](/source/protoconid) and [metaconid](/source/metaconid), are isolated from each other. In front of the metaconid, there is a small cuspule, an [anteroconid](/source/anteroconid), at the lingual side of the tooth (the side of the tongue). The central basin of the tooth is relatively deep. At the back of the tooth, the [entoconid](/source/entoconid) cusp is connected to the [posterolophid](/source/posterolophid), a crest that forms the back margin. Of the two roots, the one at the front is round and the one at the back is broad.

Although m1 is nearly rectangular, the width at the front is still smaller than the width at the back. There is a strong anteroconid. A crest, the [metalophid](/source/metalophid), reaches from the protoconid nearly to the metaconid. A small cusp, the [mesostylid](/source/mesostylid), is connected to the metaconid in front of it, unlike in ''[Miopetaurista](/source/Miopetaurista)'' and ''Aliveria''. There are two broad roots. The next tooth, m2, is similar to m1 in most respects, but the width at the front is virtually equal to the width at the back, so that the tooth is about rectangular. The back of m3 is rounded, but the tooth is still nearly rectangular. There is a long anteroconid, which is mainly connected to the metaconid. There is no metalophid. This tooth has three roots: two at the front and a larger one at the back.<ref name=MG30/>

==Range and context==
The remains of ''Lagrivea'' were probably collected by Viret at the site La Grive L5 in the village of Saint-Alban-de-Roche, department of [Isère](/source/Is%C3%A8re), southeastern France.<ref>Mein and Ginsburg, 2002, pp.&nbsp;7, 29</ref> La Grive L5 is one of several fissure filling sites in the area, collectively known as La Grive-Saint-Alban, which have yielded rich fossil faunas.<ref>Mein and Ginsburg, 2002, pp.&nbsp;7–8</ref> Another site, La Grive M, is the reference locality for the [MN zone](/source/MN_zonation) MN 7/8,<ref name=MG37/> about 13 to 11 million years ago.<ref>Steininger, 1999, fig.&nbsp;1.2</ref> La Grive L5 is one of the younger sites of La Grive, and Mein and Ginsburg proposed placing it in a separate zone MN 8.<ref name=MG37>Mein and Ginsburg, 2002, p.&nbsp;37</ref>  Other squirrels at La Grive-Saint-Alban include species of ''[Heteroxerus](/source/Heteroxerus)'', ''[Spermophilinus](/source/Spermophilinus)'', ''Palaeosciurus'', and [chipmunk](/source/chipmunk)s, and [flying squirrel](/source/flying_squirrel)s in the genera ''Albanensia'', ''Miopetaurista'', ''[Forsythia](/source/Forsythia_(flying_squirrel))'', ''[Hylopetes](/source/Hylopetes)'', and ''[Blackia](/source/Blackia)''.<ref name=MG35>Mein and Ginsburg, 2002, p. 35</ref> ''Miopetaurista neogrivensis'', ''Spermophilinus bredai'', and ''Heteroxerus huerzeleri'' are also known from La Grive L5.<ref>Mein and Ginsburg, 2002, table 9</ref> In 2012, Ginsburg and Mein described an indeterminate squirrel from the older (MN 6) site of [Sansan](/source/Sansan%2C_Gers), France, on the basis of a single p4. This tooth is similar in size to ''Lagrivea'', but differs in a narrower talonid.<ref>Ginsburg and Mein, 2012, p.&nbsp;93</ref>

==References==
{{Reflist|colwidth=30em}}

==Literature cited==
*Ginsburg, L. and Mein, P. 2012. Les Sciuridae (Rodentia) de Sansan. Mémoires du Muséum national d'Histoire naturelle 203:81–94.
*McKenna, M.C. and Bell, S.K. 1997. Classification of Mammals: Above the species level. New York: Columbia University Press, 631&nbsp;pp. {{ISBN|978-0-231-11013-6}}
*Mein, P. and Ginsburg, L. 2002. Sur l'âge relatif des différents karstiques miocènes de La Grive-Saint-Alban (Isère). Cahiers scientifiques, Muséum d'Histoire naturelle, Lyon 2:7–47 (in French).
*Steininger, F. 1999. Chronostratigraphy, geochronology and biochronology of the Miocene "European Land Mammal Mega-Zones (ELMMZ)" and the Miocene "Mammal Zones (MN-Zones)". Pp.&nbsp;9–24 in Rössner, G.E. and Heissig, K. (eds.). The Miocene Land Mammals of Europe. Munich: Verlag Dr. Friedrich Pfeil, 515&nbsp;pp.

{{Sciuromorpha|state=collapsed}}
{{Taxonbar|from=Q6472713}}
{{Good article}}

Category:Miocene rodents
Category:Prehistoric mammals of Europe
Category:Squirrels
Category:Monotypic prehistoric rodent genera
Category:Fossil taxa described in 2002

---
Adapted from the Wikipedia article [Lagrivea](https://en.wikipedia.org/wiki/Lagrivea) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Lagrivea?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.