Rodentia

1
Rodentia

• Nearly cosmopolitan distribution
• Wide spectrum of diets
• Important members of most terrestrial faunas ?
  can reach extremely high densities
• Considerable morphological diversity ?
  considerable disagreement in familial and lower
  relationships

2
Rodentia

• A single pair of persistently growing incisors in
  upper and lower jaw is covered with 2 layers of
  enamel (1 in lagomorphs).
• Incisors have a beveled tip as result of wear
• dental formula varies around I 1/1, C 0/0, P2/1,
  M 3/3 22
• Large diastema always present between incisors
  and premolars
• Rodent size ranges from 4.5 -10 g (Micromys
  minutus, pigmy mouse) to 50kg (Hydrochaeris
  hydrochaeris, Capybara).
• Largest north american rodent ? Beaver (12-38 kg)
• Most are weigh less than 500 g

3
Rodentia

• Largest mammalian order
• 43 of mammalian species
• 28 families with 2016 species
• Two suborders recognized
• Based on basic patterns in a few characteristics
• Arrangement of masseter muscles
• Skull
• Zygomatic arch
• Sciurognathi (11 families)
• Hystricognathi (17 families)

4
masseter origin
5
Jaw morphology
6
Rodent families

• Sciurognathi
• Aplodontidae Monotypic ? mountain beaver
  (Aplodontia rufa)
• Sciuridae (squirrels, etc.) 50 genera, 273
  species
• Castoridae (beaver) 1 genus 2 species
• Heteromyidae (Kangaroo rats, etc.) 6 genera, 59
  species
• Geomyidae (Pocket gophers) 5 genera, 35 species
• Muridae 281 genera, 1325 species
• Myoxidae (dormice) 8 genera, 26 species
• Dipodidae (jerboas, etc.) 15 genera, 51 species
• Anomaluridae (scaly-tailed squirrels) 3 genera,
  7 species
• Pedetidae (spring-hare) Monotypic ? Pedetes
  capensis
• Ctenodactylidae 4 genera, 5 species

7
Rodent families

• Hystricognathi
• Erethizontidae (New world porcupines) 4 genera,
  12 species
• Hystricidae (Old world porcupines) 3 genera, 11
  species
• Bathyergidae (African mole-rats) 5 genera, 9
  species
• Petromuridae (dassie rat) monotypic ? Petromus
  typicus
• Chinchillidae (chinchillas) 3 genera, 6 species
• Dinomyidae (pacarana) monotypic ? Dinomys
  branickii
• Caviidae (Guinea pigs, etc.) 5 genera, 14
  species
• Hydrochaeridae (capybara) monotypic ?
  Hydrochoerus hydrochaeris
• Dasyproctidae (agoutis) 2 genera, 13 species
• Ctenomyidae (tuco-tucos) 1 genus, 38 species
• Octodontidae (degus, etc.) 6 genera, 9 speices
• Abrocomidae (chinchilla rats) 1 genus, 3
  species
• Echimyidae (spiny rats) 20 genera, 78 species
• Agoutidae (pacas) 1 genus, 2 species
• Capromyidae (hutias, etc.) 8 genera, 20 species
• Myocastoridae (nutria) monotypic ? Myocastor
  coypus

8
Sciurognathi Aplodontidae
9
Sciurognathi Sciuridae
10
Sciurognathi Sciuridae
11
Sciurognathi Castoridae
12
Sciurognathi Heteromyidae
13
Sciurognathi Geomyidae
14
Sciurognathi Muridae
15
Sciurognathi Muridae
16
Hystricognathi Erethizontidae
17
Hystricognathi Myocastoridae