Lecture 7 Flashcards
Oldest mammal fossil
Juramaia sinensis
160Mya
Origin of Mammals
Jurassic
Early Eutherians
Small size
Lacked opposable first digit
-Not arboreal in the strict sense
Adapted for arboreal habit
Incisors varied in number
Lacked auditory bulla
Variety of ecological roles
- Insectivoty, carnivory, herbivory
- Climbers, jumpers, diggers, and generalized runners
“Insectivorans”
Quotations convention to acknowledge group for certain reasons but is NOT clade
No longer recognized taxon/clade
Taxonomic wastebasket
Superorder Afrotheria
Mammal group proposed 20 years ago based on molecular evidence
Order Afrosoricida Order macroscelidea Order Tubulidentata Order Proboscidea Order Sirenia Order Hyracoidea
End of Cretaceous Period
B/w 145-166Mya, movement of continental plates
African land mass isolated from other land masses
Adaptive radiation led to diverse forms
Superorder Afrotheria
Order Afrosoricia
Family Tenrecidae
Madagascar, Comoro Islands, and west central Africa (otter shrews)
-Endemic: Found in ONLY one particular place
Dispersed to Madagascar ~55Mya
Adaptive radiation on Madagascar
Tenrecs retain many ancestral traits
Shrew-to rabbit-sized
Long snout and small eyes
urogenital canal and anus open into a common cloaca
Some species may use rudimentary echolocation
-Generate clicks audible to human ears and imitate the echo of the clicks
Many species have spines interspersed with soft hairs
-hemicentetes has specialized quills - stridulating organ (contracts muscle, makes quills rub together to make noise)
Adaptive radiation in Tenrecidae
Some species are heterothermic
Most are insectivorous or omnivorous
Inhabit variety of habitats:
- Rainforests
- Dry deciduous forest
- Deserts
Lots of convergent evolution
- Shrew-like tenrec
- Web-footed tenrec (convergent with Northern water shrew)
- Rice tenrec (convergent with mole)
- Giant otter “shrew” (convergent with otter)
Superorder Afrotheria
Order Afrosoricida
Family Chrysochloridae
Golden moles
Fossils date to Miocene of Kenya
Highly fossorial
Convergent with:
- Notorictidae
- Talpidae (true moles)
Fossorial adaptations:
- Ears lack pinnae; ear canal covered with hair
- Eyes vestigial and covered with skin and fur
- Leathery pad on snout
- Skull conical
- Auditory bulla present, malleus greatly enlarged to detect seismic signals
- Digits 2 and 3 bear huge claws
- Forelimbs powerfully built: used for digging
- Ossified flexor tendon in forearm
- Powerful burrowers
- -Eremitalpa “swims” through loose sand using forearms, head, and shoulders
Swim through sand
Superorder Afrotheria
Order Macroscelidea
Family Macroscelididae
Monotypic order
Sengis/elephant shrews
Fossils date to Eocene of Tunisia (Western part of Africa)
Disjunct distribution
New species discovered in Tanzania in 2007
Size ranges from small shrew to small cat
Inhabit open plains to tropical forests
Feeds on a wide variety of invertebrates (insectivorous)
Some species strikingly colored
Territorial: maintain intricate trail system (move things out of trail to make quick get-away paths
Scent marking and foot drumming
Some species use behavioral thermoregulation (basking)
Long, mobile snout
Name comes from long, flexible snout used to move things out of the way
Long, slender legs adapted for running
Large olfactory lobes, hippocampus
Complete auditory bulla
Complete zygoma
hippocampus associated with memory; memorize trail systems to get away from predators
Superorder Afrotheria
Order Tubulidentata
Family orycteropodidae
Monotypic order and family
Aardvark
Sparsely inhabits sub-Saharan Africa
Fossils appear in Miocene of southern Europe, Middle East, and Africa
Powerful digger (“digging foot”)
Feeds on termites and ants
Weighs up to 65kg
Tongue is slender and protrusible
Skull elongate and conical
Dentary bone long and slender
Adults lack incisors and canines
Columnar teeth are rootless
- Consist of as many 1500 hexagonal prisms of dentine
- Teeth LACk enamel
Dismantle termite mounds and ant nests with powerful forelimbs
Aardvark burrows used as retreats by many other mammals
Almost entirely nocturnal
olfaction well-developed
Fleshy tentacles on nasal septum
-Tentacles by sinuses prevent ants/termites from getting up into nose
Infraclass Eutheria
4 Superorders:
1) Afrotheria = “Wild animals” or mammals from Africa
2) Euarchontoglires = “True ancestors” plus “rodents”
3) Laurasiatheria = mammals from Laurasia
4) Xenarthra = “strange joints
Superorder Euarchontoglires
Order Dermoptera
Family Cynocephalidae
Dermoptera refers to patagium
Cynocephalidae = dog-faced
Broad, furred patagium
Arboreal glider
Face lemur-like with large eyes
Dorsal pelage cryptic against tree bark
Southeast Asia distribution
NO powered flight
Misnomer: “Flying lemur;” not a lemur, can’t fly
Caniniform upper incisors
Pectinate lower incisors
Superorder Euarchontoglires
Order Scandentia
2 families: Tupaiidae and Ptilocercidae
Occur from India to Myanmar to islands of Sumatran Borneo and Philippines
Primitieve lineage with affinities to dermopterans and primates
Squirrel-like body
upper incisors caniniform
Upper canines reduced
Zygomatic arch has prominent hole
Post-orbital process connects with zygoma
VERY ancestral
Superficial similarities to dermopterans and primates
Superorder Euarchontoglires
Order Scandentia
Family Tupaiidae
Squirrel-like tail
Mostly diurnal to crepuscular (active at dawn or dusk)
Omnivorous
Some species arboreal; some terrestrial
