Lecture 18. Rodents 1

Carleton & Musser, 2005, p. 751 Carleton & Musser, 2005, p. 751 "We retain Brandt’s (1855) names for three of the five suborders (Sciuromorpha, Myomorpha, and Hystricomorpha), whereas some foremost rodent authorities have pointedly advised against continued employment of these Brantian epithets, especially at the subordinal rank (e.g., Landry, 1999:283; Wood, 1985). They have argued that the descriptive meaning of the terms does not strictly concord with the morphologies of included members, and that this contradiction will only continue to engender confusion. That the logical connotation of a taxon’s name should uniformly correspond to its taxonomic intention strikes us as puzzling. Not all members of the Superorder Afrotheria live in Africa, nor are all species of the Order Carnivora carnivorous. The species- to family-group ranks are rife with valid names whose logical meaning, as intended by the original descriptor, is partially inconsistent or actually misleading in terms of the currently accepted contents of the taxon, whether in strict morphological accuracy, indication of distribution, or implication of phylogenetic alliance. In reviewing 150 years of rodent classifications, we are impressed that few of our predecessors applied the features of infraorbital configuration and jaw shape in an overridingly typological touchstone of all rodent classification. Most made the distinction between, e.g., Myomorpha in its taxic sense and myomorphy as a morphological condition and routinely consulted additional traits. Thus, the hystricomorphous Dipodidae have been nearly always included within Myomorpha (in retrospect, correctly it would seem), and the sciuromorphous Geomyoidea have been considered by many to also fit within Myomorpha (in retrospect, perhaps incorrectly). And while Brandt’s taxonomic names qua morphological descriptors may not perfectly correspond to all members, they nonetheless do conform very well. The core family members of Sciuromorpha, Myomorpha, and Hystricomorpha have remained largely the same, and most, not all, do exhibit those fundamental zygomasseteric structures. More importantly, these core assemblages have survived recent scrutiny using ever more explicit principles for systematic classification and sophisticated methods for inferring phylogenetic relationship and assessing descent from a common ancestor." Carleton & Musser, 2005, p. 751 Carleton & Musser, 2005, p. 751

Rodentia Sub-orders (Mammal Species of the World, 3rd ed., 2005) Lecture 18. Rodents 1 Rodentia Sub-orders (Mammal Species of the World, 3rd ed., 2005) Sub-order Masseteric condition Mandibular condition Number of families / species Sciuromorpha protogomorphous (Aplodontidae), sciuromorphous (Sciuridae), “pseudo-myomorphous” (Gliridae) sciurognathous 3 / 307 Castorimorpha sciuromorphous 3 / 102 Myomorpha myomorphous (except Dipodidae, hystricomorphous) 7 / 1569 Anomaluromorpha hystricomorphous 2 / 9 Hystricomorpha sciurognathous (only Ctenodactylidae) hystricognathous (rest) 18 / 290 The distribution of these two important characters, the masseteric and the lower jaw condition, among the major groups of rodents is hsown in this table, Our current understading of their phyloeny indicates that the different morphologies evolved more than once, or that were lost in some groups. DIPODIDAE IS HYSTRICOMORPHOUS, BUT PHYLGENETICALLY/TAXONOMICALLY IN MYOMORPHA. SEE P. 751 OF MSW3. SEE ALSO MARCELO’S E-MAIL FROM NOV. 2008. THERE MAY BE OTHER EXCEPTIONS.

Aplodontidae Monotypic (1 species) Restricted to NW US “Primitive” rodent Protrogomorphous-Sciurognathous

Sciuridae 50 genera, 273 species Worldwide except Australia and southern South America Wide range of ecolomorphs Although Hayssen 2008 (J. Mammalogy) breaks squirrel morphology into 4 or so types. Should use!

Squirrel body plans (N. American examples) Ground Tree Flying Tamias Spermophilus Marmota Sciurus Tamiasciurus Glaucomys

Tamias minimus Least Chipmunk

Castoridae 1 genus, 2 species Holarctic Semi-aquatic Specialize on cambium

Muridae >250 genera, >1300 species Mice, rats, voles, hamsters, gerbils

Muridae: Subfamilies Murinae Old World mice & rats Cricetidae! voles Sigmodontinae New World mice & rats Gerbillinae gerbils Spalacinae blind mole-rats + 12 others!!! Alaska

Anomaluridae Scaly-tailed squirrels 3 genera, 7 species Western-central Africa

Suborder: Hystricomorpha Africa AKA “Phiomorpha” Bathyergidae mole rats Hystricidae Old World porcupines Petromuridae rock rats, dassie rats Thryonomyidae cane rats

Suborder: Hystricomorpha South America AKA “Caviomorpha” Erethizontidae Chinchillidae Dinomyidae Caviidae Hydrochaeridae Dasyproctidae Agoutidae Ctenomyidae Octodontidae Abrocomidae Echimyidae Capromyidae Myocastoridae

Erethizontidae New World porcupines 4 genera, 12 species Lowland tropics to montane forests, deserts, coniferous forests Herbivores