|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Calomys (Bensonomys) stirtoni
Mammalia - Rodentia - Cricetidae
It was recombined as Calomys (Bensonomys) stirtoni by Baskin (1978); it was recombined as Calomys stirtoni by Dalquest (1980); it was recombined as Bensonomys stirtoni by Martin et al. (2002).
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.
|C. W. Hibbard 1953||Description of holotype - The coronoid process, articular condyle,
and angular process of tbe jaw are missing. The stage of wear in the
molars is that of a young adult. The masseteric ridge is well formed
and ends in a pronounced knob in front of tbe anterior root of m2.
Its anterior end is just posterior to tbe border of the mental foramen.
The transverse width of tbe diastemaI region is as great as in Peromyscus difficilis (Allen)from Acultzingo, Vera Cruz, Mexico, but the diastemal region has a shorter anteroposterior length. The capsular process for the base of the incisor protruded enough so that a valley existed between it and the coronoid process. The molars are low-crowned.
m2 has a deep anteromedian groove on tbe face of the anteroconid.
The first lingual (internal) reëntrant vaIley between the anteroconid
and the metaconid is broad and deep. The first labial (external)
reëntrant valley is slightly wider. The deep anterior groove and the
first reëntrant vaIleys produce distinct anterolingual and anterolabial conulids on the anteroconid. The second lingual and labial reëntrant valleys are broad. The valley between the entoconid and tbe posteriorhcingulum is narrow. The cingulum along the labial side of the tooth is well developed between the labial edge of the anteroconid and the protoconid, also between tbe protoconid and the hypoconid.
The cingulum projects upward, closing off the basal entrance to the
external valleys and forming shallow basins which in later stages of
wear would produce small depressed enamel islets or pits on the occlusal surface.
m2, in comparison with m2 of Peromyacus, has a greater transverse
width in relation to its anteroposterior length. The anterior cingulum
(anterolophid) joins tbe base of the protoconid, producing a distinct
pit between the cingulum and the protoconid. The external cingulum
closes the vaIley between tbe protoconid and tbe hypoconid. The
posterior cingulum joins the entoconid, forming a pit between the
cingulum and the entoconid ; therefore tbe posterior internal reëntrant valley of m2 is not open, as is that of m1.
m3 is not reduced. The crown of the tooth is broad anteriorly
and narrows posteriorly. The anterior cingulum (anterolophid) joins
the base of tbe protoconid, forming a deep, narrow pit. The external
reëntrant valley extends halfway across the tooth and has a small
cingular ridge at its mouth. A posterior internal reëntrant valley
was formerly present, as is indicated by a smalI, isolated enamel pit.
The cingulum doses tbe base of tbe anterointernal reëntrant valley.
The valley in a later stage of wear would form a small enamel islet
with a depression on its surface. The cusps of the molars are alternate.