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Morganucodon Early Mammals: Morganucodontids Jeholodens Early Mammals: Triconodonts Till recently, known only from teeth and a few other skeletal fragments.

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Presentation on theme: "Morganucodon Early Mammals: Morganucodontids Jeholodens Early Mammals: Triconodonts Till recently, known only from teeth and a few other skeletal fragments."— Presentation transcript:

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2 Morganucodon Early Mammals: Morganucodontids

3 Jeholodens Early Mammals: Triconodonts Till recently, known only from teeth and a few other skeletal fragments. Similar to Morganucodontids, except the cusps are linear.

4 Discovered in China a few years ago Mammalian pectoral girdle –(scapula and clavicle only– loss of coracoids and interclavicle) Pelvic girdle is still ancestral –ilium, ischium and pubis are separate, epipubic bones are present. Sprawling posture – limbs not rotated under body. Demonstration of mosaic evolution. –pectoral girdle is derived, but the pelvic girdle is primitive. Triconodonts cont., Jeholodens

5 Repenomamus giganticus Triconodonts cont.,

6 Kryptobataar. Early Mammals: Multituberculates

7 Ptilodus Multituberculates cont.

8 Paraphyletic- used informally Mid Jurassic Earliest bifunctional teeth - single cheek tooth with grinding and shearing function. Tribosphenic molars, ( primitive tooth type for living mammals) Early Mammals: Pantotheres

9 Bishops, Ausktribosphenos Early Mammals: Recent finds

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12 Morganucodontids Monotremes Trichodonts Multituberculates Pantotheres Metatherians Eutherians Prototheria

13 Monotremes

14 Steropodon galmanii 125 MYA (Lightning Ridge sandstone deposits, New South Wales) Teeth resemble those of a juvenile platypus Second find- Kollikodon ritchiei, 1995, suggests diversification by early Cretaceous Archer et al 1985 Monotremes: Fossil Record

15 Monotremes: Fossil Record cont. Tertiary Fossils Obdurodon insignis (1970), O. dicksoni (Archer 1992) Miocene Kept teeth at maturity May have been terrestrial Megalibgwilia ramsayi (Griffiths 1991), Zaglossus hacketti Giant echidnas Z. hacketti = largest monotreme ever

16 Monotreme origins and distribution: Paleocene platypus tooth discovered in Argentina (Pascual, 1992)

17 Monotremes Often called ‘primitive’… a misnomer Mosaics of primitive and derived traits Tachyglossus - short-beaked echidna

18 Monotremes: Primitive characters

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20 Reproductive characters

21 Monotremes: Derived characters

22 Tachyglossidae - Echidnas (2 G, 2 s)

23 Tachyglossidae - continued Atelerix frontalis Zaglossus bruijni Tachyglossus aculeatus

24 Ornithorhynchidae (Platypus) Ornithorhynchus Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences No. 1372, Platypus Biology: Recent Advances and Reviews, Jul. 29, 1998, pp No. 1372, Platypus Biology: Recent Advances and Reviews

25 Ornithorhynchidae (Platypus) Ornithorhynchus

26 Grant et al 1998

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