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Primates. Primates: Characteristics. In general, characters used to define primates are not unique to the group, and tend to be associated with arboreality. Teeth are bunodont and brachydont. They exhibit specialization of the hands and digits: Nails vs. claws. Pads. Ridges.
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Primates: Characteristics • In general, characters used to define primates are not unique to the group, and tend to be associated with arboreality.
Teeth are bunodont and brachydont. They exhibit specialization of the hands and digits: Nails vs. claws. Pads. Ridges. All primates have a post-orbital bar with some level of binocularity. Enalrgement of Cerebral cortex. Reduced olfaction and increased visual importance (stereoscopy – color). Diet. Sociality. Primates: Characteristics
Primate Evolution • Formerly, primates were divided into prosimians and anthropoids. However, this results in some unnatural groups. • Today, we divide the primates into Strepsirhines and Haplorhines. • Haplorhines include Tarsiers and simians. Strepsirhines include lemurs and lorises.
Primate Evolution • Note the position of the Plesiadapids and the Paromomyids.
Primate Evolution • The floor of the auditory bullae in primates are covered by the petrosal bone. • Primate jaws have little lateral mobility (compared to rodents). • Primates are plantigrade – some forms have lost the hallux and/or pollex.
Primate Evolution • Earliest fossils date to the Cretaceous of Europe and North America. • Plesiadapis lacked a postorbital bar, was relatively small and squirrel-like. • The tibia and fibula are separate, allowing rotation of the hind-limb. Why is this important? • Digits are long, and terminal digits had claws, not nails.
Primate Evolution • What can you infer from the skull structure of Plesiadapis? • Note: teeth, jaw, size of braincase.
Primate Evolution • Adapids are derived from the Plesiadapids, and show up in the Eocene of Eurasia and North America. They are possible ancestors to modern lemurs. The forests of Europe and N. America were tropical in the Eocene. • Smilodectes had a postorbital bar, long tail, binocularity, no diastema, and an offset first digit on each foot. They too were small.
Primate Evolution • Omomyids probably evolved from the plesiadapids in the Oligocene and Eocene of North America and Europe. Tetonius and Necrolemur had large eyes (nocturnality?), binocularity, a short rostrum, underived teeth, large canines. • Probably gave rise to the tarsiers.
Primate Evolution • Modern new world families include the Callithrichidae and Cebidae. Their modern distribution is in south and central America. Fossil record is poor. • Cercopithecidae of the old world have a better fossil record, including the Oligocene through Recent epochs.
Primate Evolution • The jaw of Parapithecus has a condyle which is high on the ascending ramus – very similar to that of modern cercopithecid primates. These are ancestral to hylobatids and hominids. • Did primates evolve in trees or on the ground? Consider the morphological characteristics we have covered.
Strepsirhines • 7 families, primarily in Madagascar. • These are the “prosimians” – lemurs and lorises. • Differ from Haplorhines by possession of a rhinarium. • Possess a bicornate uterus. • Dental formula is 2/2, 1/1, 3/3, 3/3.
Strepsirhines • Placenta is noninvasive epitheliochorial. • Young are relatively small compared to female. • These traits are plesiomorphic, and unite the strepsirhines, probably as a monophyletic group.
Strepsirhine: Daubentoniidae • Aye-ayes: Daubentonia madagascariensis. • Monotypic. • Derived from same ancestral stock as lemurs and lorises. • Solitary, nocturnal insectivores of lowland forests in Madagascar. Note long finger for tapping and extraction. • Virtually extinct – but one protected by custom, now viewed as ‘evil.’
Strepsirhine: Daubentoniidae • What do you make of this skull of an Aye-aye?
Strepsirhine: Loridae • Lorises and pottos: 4 genera and 6 species. Range includes sub-saharan Africa, India, Southeast Asia, Indonesia, and the Philippines. • Small, flattened faces, nocturnal, arboreal, dark thick wooly fur. • Pollex is 180º from remaining digits – semi opposable.
Strepsirhines: Loridae • Second digit is reduced in most. • Second toe modified as ‘toilet claw’ in some. • Insectivorous and/or frugivorous. • Live singly or paired, have vocalizations w/ some facial expressions – also scent mark.
Strepsirhines: Galagonidae • Bushbabies of Africa. 4 genera and 11 species. • Arboreal – studied extensively because of leaping ability. Have long hind-limbs and a long tail. • Galagoides demidoff (60g) to Otolemur crassicaudatus (1.2Kg). • Pentadactyl w/ second toe modified as toilet claw. Insectivorous/omnivorous.
Strepsirhines: Galagonidae • Live in groups of up to 9 animals. • Use urine-marking, facial expressions, body posture, and vocalizations that sound like a human baby crying (hence the name).
Strepsirhine: Galagonidae • Note the incisiform canine.
Strepsirhines: Lemuridae • 4 genera and 10 species. • Madagascar only, diurnal or crepuscular, and arboreal, but may spend time on ground. • Differ from other strepsirhines by small eyes (dirunal), and rostrum. • Eat fruit, flowers, and vegetation. • Lower incisors and canines form procumbent dental comb for auto and allogrooming.
Strepsirhine: Lemuridae • All species have ear tufts. • Eulemur macaco shows sexual dichromatism. • All except Lemur catta (ring-tailed lemur) use leaping and clinging for locomotion. Lemur catta is quadrupedal and climbs. • Social groups up to 20, scent and urine marking. Sternal glands, cutaneous arm glands. Vocal, posture, and facial communication.
Strepsirhine: Megaladapidae • Sportive lemurs – nocturnal and arboreal. Eat leaves, bark, fruit, and flowers. • Vertical clinging and leaping locomotion, has prehensile thumb. • Solitary, some scent and urine marking. Extensive vocal communication.
Strepsirhine: Cheirogaleidae • Dwarf and Mouse lemurs: 4 genera and 7 species, all in Madagascar. • Large forward facing eyes, muzzles, arboreal and nocturnal. Locomotion is squirrel-like, but Microcebus is a leaper. • Insectivorous (Microcebus) or insects and fruit. • Solitary or paired, posture, facial, vocal communication, although less than in other strepsirhines.
Strepsirhine: Indridae • 3 genera and 5 species, all in Madagascar. Nocturnal and arboreal. • Includes Propithecus (sifakas – look like me) and Indri, the largest Strepsirhine primate (10Kg, short tail). Eat leaves, fruit, flowers, and bark. • Vertical clinging and leaping. Hind limb dominance. • Groups of3-6, Vocal, scent, facial, communication.
a) lemur, b) sifaka, Indridae, c) aye-aye, and d) potto, Loridae.
Primate Evolution Haplorhines
Note: haplorhines are found in Africa, Asia, and Central & South America. Also, they have spatulate incisors, a hemochorial placenta, and a postorbital plate.
Tarsiidae • A single genus w/ 5 species. • Found in Indonesia, Malay archipelago, and the Philippines. • Fossil forms from N. America and Europe. • Extreme ability to rotate head. • Crepuscular & nocturnal. Vertical clingers and leapers. • Eat insects, lizards, and spiders.
Tarsiers • Form pair bonds. • Territorial. • Produce a single precocial young.
