INFRACLASS EUTHERIA (= "Placentalia")

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• Placental mammals
• 18 Orders (plus 4 extinct Orders), about 3,800 species
• the ecologically dominant mammals of the Cenozoic
• Characteristics of Placental Mammals
  1. Chorioallantoic placenta (Fig. 9.11B, pp. 153-156)
  2. primitive dental formula: 3/3-1/1-4/4-3/3 = 44

• Learn more about Eutherians from
  1. the University of California Museum of Paleontology or
  2. the University of Michigan Animal Diversity Web

Order INSECTIVORA (Eulipotyphla)

shrews, moles, hedgehogs (4 or 5 families, 390 species)

1. The Order Insectivora has been used as a scrapbasket for a variety of very small, relatively unspecialized, insectivorous eutherians with cheekteeth simple, tritubercular or quadritubercular.
2. Tree shrews, elephant shrews, and dermopterans have been placed in separate orders.
3. Insectivora has been restricted to the Lipotyphla (shrews, solenodons, moles, hedgehogs, tenrecs and golden moles).
4. However, molecular evidence indicates golden moles and tenrecs belong in the Afrotheria, a taxonomic group that also includes elephants, sea cows, hyraxes, aardvarks, elephant shrews.  A new order "Afrosoricida" comprises Chrysochloridae (golden moles) and Tenrecidae (tenrecs).
5. The Order Insectivora is now restricted to to the Eulipotyphla (shrews, solenodons, moles, hedgehogs, and Nesophontes).
6. CHARACTERISTICS
   1. simplified hindgut lacking a caecum [Fig. 6.2]
   2. small to medium sized
   3. pentadactyl
   4. plantigrade
   5. long pointed snouts
   6. sharp teeth
   7. pinnae and eyes are usually small to absent
   8. annular tympanic bone [absence of auditory bullae]
   9. smooth cerebrum

• Learn more about Insectivorans from
  1. the University of Michigan Animal Diversity Web
  2. The Insectivora of Texas

Families

1. Erinaceidae--hedgehogs [figs. 11.2, 11.3] and moon rats
   1. Ethiopian, Palearctic, Oriental
   2. 7 genera, 21 species
   3. Most with spiny (barbless) pelage, roll into ball for defense
   4. moon rats (gymnures) lack spines; when threatened, produce a foul smell.
   5. omnivorous: diet consists of invertebrates, small vertebrates, eggs, fruit.
   6. Skull and dental characteristics
      1. low cusps (unlike shrews or moles): used in crushing and grinding
      2. first lower incisors are well developed, but not as large as in shrews
   7. estivate in response to low food availability
   8. hedgehogs as pets
   9. The Compleat Internet Hedgehog Atlas
      
      

2. Talpidae--moles [fig 11.4] Holarctic, Oriental 17 genera, 42 species moles and shrews of the United States from enature Scalopus aquaticus the eastern mole [Fig. 5.18] occurs in South Texas Fossorial [fig. 11.5] Convergent evolution in all faunal regions [Fig. 11.8]  zygomatic arch complete  eyes minute ears lack pinnae modifications of the forelimb and pectoral girdle [Fig. 11.4] touch receptors (Eimer’s organ) on snout [Figs. 6.4, 20.7] Condylura, the star-nosed mole Old World desmans feed on aquatic invertebrates and fish

   Neurotrichus gibbsii--Shrew-mole; photograph by Dr. Lloyd Glenn Ingles, California Academy of Sciences Copyright © 2000 California Academy of Sciences; used with permission

3. Soricidae--shrews [figs. 11.11] Holarctic, Ethiopian, Oriental, Neotropical (to northern Colombia) largest family in order (23 genera, 312 species) moles and shrews of the United States from enature The Desert Shrew, Notiosorex crawfordi, is common in South Texas constitute about 60% of individuals in community composition studies when pitfalls are used rather than Sherman or other live traps (!) 2.5g (smallest living mammal) - 180 g Long slim snout, small eyes, ears usually visible skull characters (Fig. 11.12) no zygomatic arch I1, large hooked strongly procumbent lower incisors) high metabolic rate (must eat almost constantly) saliva toxic in some (e.g. Blarina, Fig. 6.12) Rudimentary echolocation in Sorex and Blarina to locate prey Caravanning in crocidurines  more information from the shrew site by Werner Haberl

   Sorex vagrans--Vagrant Shrew; photograph by Dr. Lloyd Glenn Ingles, California Academy of Sciences. Copyright © 1999 California Academy of Sciences; used with permission

4. Solenodontidae--solenodons [fig. 11.9]
   1. Neotropical (Greater Antilles - Hispaniola and Cuba, until recently in Puerto Rico)
   2. 1 genus, 2 species
   3. large size, up to 600 g
   4. Feed primarily on invertebrates
   5. high frequency clicking for echolocation
   6. elongate, flexible, shrew-like snout for locating food
   7. neurotoxic saliva injected with grooved lower incisor [Fig. 11.10]
   8. more information from Alexander Ferworn, Ryerson University
   9. , more on the Solenodon 

Order AFROSORICIDA

• Molecular evidence [Fig. 11.6] indicates golden moles and tenrecs belong in the Afrotheria, a taxonomic group that also includes elephants, sea cows, hyraxes, aardvarks, elephant shrews.  A new order "Afrosoricida" comprises Chrysochloridae (golden moles) and Tenrecidae (tenrecs).

1. Tenrecidae--tenrecs and water shrews Ethiopian urogenital and anal opening terminating in a cloaca Tenrecs [figs. 11.7A, B] adaptive radiation of 8 genera & 21 from Madagascar many are hedgehog-like, can roll into ball with spines Tenrec Resources and Information by David Kupitz Otter shrews 2 genera and 3 species West-central Africa large size Potamogale, the giant African otter shrew [Fig. 11.7C]: up to 650 mm and 4 kg

   Hemicentetes semispinosus Lowland Streaked Tenrec; photograph by  Gerald and Buff Corsi, Copyright © 2000 California Academy of Sciences; used with permission

2. Chrysochloridae--golden moles Ethiopian 7 genera, 18 species resemble marsupial moles and true moles Adaptations of the forelimb for burrowing [p. 76] Uses head and forefeet to burrow

   Chrysochloris asiatica; Cape Golden Mole; Photographer: Dave Mangham; used with permission.  Copyright © 2005 Dave Mangham/www.wildlifephotos.org.uk

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