|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Mammalia - Rodentia - Cricetidae
It was recombined as Copemys longidens by Clark et al. (1964) and Lindsay (1972).
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|E. R. Hall 1930||Size large; tooth row, and individual teeth, long and relatively narrow; molars short crowned and without accessory cusps; Mm3 relatively large; medial border of m3 with a posterior pit as well as an naterior reentrant valley; space between m3 and coronoid process of medium width for Peromyscus, relatvely flat and with one large foramen.|
|D. F. Hoffmeister 1959 (Miochomys niobrariensis)||A cricetid rodent in which the cheek teeth have both the lingual and
labial cusps elevated and of nearly the same height; cingular portion of the cusps wear least; reentrant angles of two sides of tooth
nearly opposite and nearly continuous as transverse valleys across low central axis; the two transverse valleys across tooth give
M1 the appearance of three separate segments,
namely (1) anterocone, (2) protocone-paracone, (3) hypocone-metacone (for terminology, see Hoffmeister, 1951 :11); anterocone
tends to be isolated from other cusps; mesoloph very weakly developed, but extending almost to cingulum; posteroloph
apparently present, but, if so, weakly developed and fusing with posterior border of metacone.
Maxilla.- The ventral two-thirds of the left infraorbital plate and that portion of the maxilla bearing M1-2 are preserved. The
anterior border of the infraorbital plate projects increasingly anteriad as it ascends dorsalIy, and in this detail resembles the
plate in Oryzomys more than that of any other Nearctic genus. The anterior border of the plate is only slightly more medial
than its posterior border, and if the structure is similar otherwise to Recent forms,this would result in a wide infraorbital fissure.
The outer surface of the plate is more concave than in other forms, being similar to Oryzomys in th is respect. No tubercle or
fossa is present ventral to the infraorbital
plate for attachment of M. masseter superficialis.
Probably this muscle was weakly developed;
it did not necessarily attach elsewhere.
The absence of this tubercle is quite in distinction to the condition in Reithrodontomys (subgenus Reithrodontomys), Reithrodontomys
(subgenus Aporodon), and Baiomys. The first molar is relatively farther posterior, in relation to the infraorbital
plate, than in ot her Recent genera of Nearctic cricetid rodents.