Lab 11-Order INSECTIVORA
The
order Insectivora is a collection of primitive yet
each highly derived groups, the phylogenetic
relationships of which remain obscure.
Older classifications divided Insectivora into
two suborders: Lipotyphla
(Soricidae, Talpidae, Erinaceidae, Solenodontidae, Tenrecidae, and Chrysochloridae)
and Menotyphla (Macroscelididae
and Tupaiidae [the latter sometimes grouped as basal
Primates]).
Both
the Macroscelididae and Tupaiidae
are now classed as separate orders (Macroscelidea and
Scandentia, respectively), and will be so treated
here.
An
hypothesis of phylogenetic relationships among the Lipotyphlan families, what now comprise the Order Insectivora with the removal of both Macroscelidids
and Tupaiids, is illustrated below. This phylogeny, however, is at odds with very
recent DNA sequence data that suggest that the African Chrysochloridae
and Tenrecidae form a phylogenetic
unit independent of the remaining Lipotyphlan
groups. Together, these two families
have been placed in the Order Afrosoricida.
We
will follow Martin et al., and use the traditional view of the Order Insectivora to include all six Lipotyphlan
families.
suggested phylogenetic
relationships among extant insectivores (the inclusion of Chrysochloridae
and Tenrecidae as the sister group to the Soricidae, Talpidae, and Solenodontidae, is not supported by DNA sequence data).
general
characters:
1.
size very
small to medium
2.
foot
posture usually plantigrade
3.
snouth
generally elongate
4.
pelage usually
consisting of only one kind of hair of uniform length
5.
cerebral
hemispheres smooth, lacking complex folding
6.
cheekteeh
relatively simple, tribubercular or quadritubercular
Family SORICIDAE
(shrews)
diagnostic
character: condyloid process of lower jaw with
two condyles (only one in all other
mammals)
|
general
characters: 1.
size
small (6-30 cm) 2.
eyes
small, visible 3.
forefoot
unspecialized 4.
pelage
short, soft 5.
pinna
present, small 6.
no zygomatic arch 7.
no
auditory bulla
8.
first upper
incisor large, hooked, and with cusp at proximal base of tooth 9.
upper
molars tritubercular to quadritubercular,
with sharp cusps; crowns with W-shaped ectoloph (dilambdodont) 10. pubic
bones separate 11. shallow
cloaca sometimes present |
|
dental
formula:
|
3 1 1- 3 3 1-2
0-1 1 3 |
= 26-32 |
common
genera: North America - Blarina
(short-tailed shrews), Cryptotis
(small-eared shrews), Microsorex
(pygmy shrew), Notiosorex
(desert shrews), Sorex
(long-tailed shrews). Old World – Chimarrogale (Asiatic
water shrews), Crocidura
(white-toothed shrews), Diplomesodon
(pie-bald shrew), Myosorex
(mole shrews), Nectogale
(webbed footed water shrew), Neomys
(water shrews), Scutiosorex
(hero shrew), Suncus
(musk shrews)
range: New World – North America south to
northwestern South America; Old World – Eurasia, Africa (absent from
Australasia)
Crocidura (Old World white-toothed shrew)
|
4th upper right premolar
and 1st molar of Sorex vagrans |
first two lower left molars of Sorex vagrans |
Family TALPIDAE
(moles)
diagnostic characters:
1.
humerus
usually blocky, often nearly as wide as long, articulating with scapula and
clavicle
2.
forefoot
projecting outward and backward in most taxa; elbow
rotated upward
|
general
characters: 1.
size
small (9-45 cm) 2.
eyes
very small, visible 3.
forefoot
usually broad, paddle-shaped, adapted for digging (unspecialized or webbed in
some) 4.
pelage
short, soft, without spines 5.
pinna
very small or absent 6.
zygomatic
arch complete, slender 7.
auditory
bulla present, incomplete 8.
incisors
simple, first upper incisor directed downward and backward 9.
upper
molars tritubercular to quadritubercular,
with sharp cusps; crowns with W-shaped ectoloph (dilambdodont) 10. pubic
bones separate 11. no
cloaca |
|
dental
formula:
|
2-3
1 2-4 3
1-3 0-1 2-4 3 |
= 34-44 |
common
genera: New World – Condylura (star-nosed mole), Neurotrichus (American shrew-mole), Parascalops (hairy-tailed
mole), Scalopus
(eastern mole), Scapanus
(western moles); Old World – Desmana
(desman), Mogera
(common moles), Talpa
(European moles),Urotrichus
(Old World shrew-mole)
range: North America and Eurasia (absent from South
America, Africa, and Australasia)
Scapanus latimanus (broad-footed mole)
|
|
|
1st and 2nd upper
right (left) and lower (right) molars of an eastern mole (Scalopus)
|
Talpa europea (European mole) |
Neurotrichus gibbsi (American shrew-mole) |
|
Galemys pyrenaicus (Pyrenean desman) |
|
Family ERINACEIDAE
(hedgehogs,
moonrats or gymnures)
divided
into two subfamilies: Erinaceinae (hedgehogs, all of which have well-developed
spines) and Echinosoricinae (moonrats
or gymnures, all of which lack spines, but have
coarse fur instead)
diagnostic
characters: upper molars quadratuberculate with short, rounded cusps, not sharp
vertical shear-faces; crowns lack W-shaped ectoloph
|
general
characters: 1.
size
small to medium (15-65 cm) 2.
eyes
present, visible 3.
forefoot
unspecialized 4.
pelage with
spines; or coarse if without 5.
pinna
present, well developed 6.
zygomatic
arch present, complete, robust 7.
auditory
bulla composed on basisphenoid wing medially 8.
first
upper incisor large, canine-like 9.
pubic
bones united in short symphysis 10. no
cloaca |
|
dental
formula:
|
2-3
1 3-4 3
3 1 2-4
3 |
= 36-44 |
common
genera: Echinosorex (greater gymnure),
Erinaceus
(Eurasian and African hedgehogs), Hemiechinus
(long-eared hedgehog), Hylomys
(lesser gymnure), parechinus (desert hedgehog)
range: Old World – Eurasia and Africa (absent from
New World, Australasia); gymnures occur only in
Southeastern Asia and Indonesia
Erinaceus europaeus (European hedgehog)
upper
right (above) and lower left (below) tooth rows
of
Erinaceus europaeus
Erinaceus algirus (Algerian hedgehog:
Subfamily
Erinacinae)
Hylomys suillus (lesser moonrat:
subfamily
Echinosoricinae)