Lagrivea
Lagrivea Temporal range: Middle Miocene (MN 7/8)
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Rodentia |
Family: | Sciuridae |
Genus: | †Lagrivea Mein and Ginsburg, 2002 |
Species: | †L. vireti
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Binomial name | |
†Lagrivea vireti Mein and Ginsburg, 2002
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Lagrivea is a fossil genus of squirrel from the Middle Miocene of France. The single species, L. vireti, is known from three mandibles (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 complex in Saint-Alban-de-Roche, southeastern France. Lagrivea was a large tree squirrel with flat lower incisors and a large, triangular fourth lower premolar (p4). Each of the four cheekteeth (p4 and three molars, 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
Description
Variable | Measurements (in mm) |
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Depth of mandible at m1 | 8.5, 8.7, 9.2 |
Diastema 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, 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,[1] and can be distinguished from the fossil squirrels Palaeosciurus, Aliveria, and Ratufa obtusidens by its larger size.[2]
In the mandible, the
The cheekteeth increase regularly in size from front to back.
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, reaches from the protoconid nearly to the metaconid. A small cusp, the mesostylid, is connected to the metaconid in front of it, unlike in 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.[2]
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
References
- ^ a b c d e f Mein and Ginsburg, 2002, p. 29
- ^ a b c d Mein and Ginsburg, 2002, p. 30
- ^ McKenna and Bell, 1997, p. 121
- ^ Mein and Ginsburg, 2002, fig. 43
- ^ Mein and Ginsburg, 2002, pp. 29–30
- ^ Mein and Ginsburg, 2002, pp. 7, 29
- ^ Mein and Ginsburg, 2002, pp. 7–8
- ^ a b Mein and Ginsburg, 2002, p. 37
- ^ Steininger, 1999, fig. 1.2
- ^ Mein and Ginsburg, 2002, p. 35
- ^ Mein and Ginsburg, 2002, table 9
- ^ Ginsburg and Mein, 2012, p. 93
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 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. 9–24 in Rössner, G.E. and Heissig, K. (eds.). The Miocene Land Mammals of Europe. Munich: Verlag Dr. Friedrich Pfeil, 515 pp.