ACNE Definition Inflammation of sebaceous follicles Follicle sebaceous gland follicular canal hair.
Mammal characteristics Soft anatomy Skin glands (sweat, scent, sebaceous) Lactation Hair
description
Transcript of Mammal characteristics Soft anatomy Skin glands (sweat, scent, sebaceous) Lactation Hair
Mammal characteristics
Soft anatomy
Skin glands(sweat, scent, sebaceous)
Lactation
Hair
Diaphragm
4-chambered heart
High metabolic rate
Hard anatomy (i.e., in fossil record)
Three ear ossicles
Single bone in mandible
Complex teeth (heterodont & diphyodont)
Trirachodon Cynognathus
Therapsida – advanced cynodonts
Probainognathus
Jaw evolution – pelycosaur to mammal
Secondary Palate
Secondary Palate
Procynosuchus Probainognathus CanisPrimitive cynodont advanced cynodont modern mammal
premaxilla
maxilla
palatine
PELVIS & HIND LIMB
Posterior Lateral
Pelycosaur
Dimetrodon
Therapsid Thrinaxodon
HEAD ARTICULATION occipital atlas - axix condyle
Pelycosaur
Dimetrodon
Therapsid Thrinaxodon
Mammal
Felis
Feeding1) expansion of temporal opening, elaboration of
jaw muscles2) reduction in post-dentary jaw bones, “second”
jaw articulation3) tooth specialization (heterodonty)
Breathing1) secondary palate2) reduction in lumbar ribs, formation of ribcage (& diaphragm?)3) nasal turbinals (temp. & water conservation)
Posture & locomotion1) double occipital condyle, atlas & axis2) enlargement of limb girdles3) specialization of lumbar & sacral regions4) vertical orientation of limbs5) formation of a heel bone
Hearing 1) reduced size & flexible attachment of post-
dentary 2) reduction in size of stapes
MAMMALIAN “GRADE” TRENDS IN CYNODONTS
LOBE-FIN AMPHIBIAN PELYCOSAURFISH
MAMMAL
AMPHIBIAN
CYNODONT
Evolution of the ear
Synapsids -- size and position of stapes
Sphenacodont pelycosaurs
Advanced cynodonts
Synapsids – reduction of post-dentary jaw elements (lateral views)
Dimetrodon primitive theriodont
primitive advanced cynodont cynodont
Morganucodon primitive therian
Therapsid – mammal ear transition
Sorex (Recent shrew) – ear region
TYMPANIC(angular)
MALLEUS (articular)
Synapsids -- jaw machanics
Trithelodont (Ictidosaur)
Jaw mechanics - development of double articulation
Early mammal (or proto-mammal?) Morganucodon (late Triassic)
MORGANUCODONTS vs ADVANCED CYNODONTS
CONTRASTS BETWEEN LATE TRIASSICVERTEBRATES
EARLY DINOSAURS medium-large sizedherbivores & carnivoresprobably diurnal, some endothermic
CROCODILESsmall-medium sized, carnivores
LATE THERAPSIDSSmall-medium sized, probably nocturnalherbivores (tritylodonts) insectivores (ictidosaurs)carnivores (cynodonts)
EARLY MAMMALSVery smallInsectivoresprobably nocturnal, endothermic
Coelophysis (carnivorous dinosaur)
Tritylodon (herbivorous therapsid)
Morganucodon(insectivorous “mammaliaform”)
3 meters
1 meter
10 cm
Plateosaurus(herbivorous dinosaur)
10 meters
LATE TRIASSIC VERTEBRATES
Late Permian (250 mya)
Late Triassic (210 mya)
Pelycosaurs& early therapsids
(worldwide)
Cynodonts(worldwide)
Earliest mammals(Laurasia)
Late Jurassic (150 mybp)
Late Cretaceous (70 mybp)
Diversification ofearly mammals
(Eurasia & N. Amer.)
Origin & diversification of
therians(worldwide)
Isolation of southerngroups