click below
click below
Normal Size Small Size show me how
Modern mammals
Characteristics of modern mammals
| part of body | characterisitics |
|---|---|
| trends in organization from mammal-like amniotes to mammal | enlargement temporal opening skull, dentary bone enlarged, maxillary & palatine bones extended medially & posteriorly, change 1 occipital condyle to 2, homodont to strong heterodont, limbs beneath body, recuction in # carpal & tarsal bones |
| skeletal | single dentary bone with dentary-squamosal articulation, 3 ossicles in middle ear, 2 occipital condyles |
| soft tissue | hair/fur, 4-chambered heart with functional left aortic arch (birds right aortic arch, reptiles both), muscular diaphragm, females with mammary glands (lactogenic), enucleate red blood cells (no nucleus= better O2 capacity) |
| not unique to mammals or exceptions exist | Corpus collosum (connects 2 hemispheres of brain- not in monotremes/marsupials), Placenta (Eutherians, not marsupials), homeothermy (birds, and uncertain in some mammals) |