early hominins

Question 1

Carpolestes simpsoni

Answer 1

Paleocene: Carpolestes simposoni was a plesiadapid who had an opposable big toe with a nail and a petrosal bulla. However, it did not have forward-facing eyes and a postorbital bar. This data supports Sussman’s proposal that grasping evolved for fruit and that orbital convergence evolved later for visual predation.

Question 2

Plesiadapids

Answer 2

Paleocene: It is debated whether plesiadapids are euprimates or archaic primates, because they had some derived primate traits but lacked others. They had opposable toes/thumbs and a petrosal bulla, but lacked orbital convergence and a postorbital bar. They also had small brains, prognathic faces, and rodent-like incisors.

Question 3

Paleocene

Answer 3

[65-55 mya] At the end of the Mesozoic, there was an asteroid or comet impact that caused the extinction of the dinosaurs. Small mammals survived through the resulting disaster; the circumstances during the Paleocene favored them because there were no large predators left and it was warm. Flowering plants evolved, and insects increased in number; primates may have taken advantage of this.

Question 4

Eocene

Question 5

Adapoids

Answer 5

Eocene: Diurnal, frugivorous, gregarious, arboreal quadrupeds with ring-like ears Had hands and feet with nails and a supple flexible spine.Notharctus was at a relatively advanced stage of primate evolution: had grasping hands and feet, nails insttead of claws, not extremely prognathic, stereoscopic vision.

Question 6

Omomyoids

Answer 6

Eocene: Nocturnal, insectivorous, solitary, vertical clingers and leapers with tube-like ears. Reduced snout, enlarged orbits. Resembled a tarsier. Necrolemur had large eye sockets for nocturnal life.

Question 7

Late Eocene/Oligocene

Question 8

Candidate for Earliest Anthropoid

Answer 8

Eosimias centinnicus, China, 40-45 mya

Question 9

Four taxa from Late Eocene/Oligocene

Answer 9

Proteopithecidae and Parapithecidae (stem anthropoids with 2.1.3.3. dentition)Propliopithecidae and Oligopithecidae (stem catarrhines with 2.1.2.3. dentition)

Question 10

Parapithecidae vs. Propliopithecidae [Late Eocene/Oligocene]

Answer 10

Parapithecidae: a stem anthropoid. Dentition of 2.1.3.3. Smaller (squirrel-sized), slightly relative smaller brain, an X-4 molar cusp.Propliopithecidae: a stem catarrhine (additional steps away from anthropoids). Dentition of 2.1.2.3. Slightly larger, relatively larger brain, Y-5 molar pattern.

Question 11

Early Miocene

Question 12

Proconsulids

Answer 12

Miocene: it is possible that later hominoids rose from proconsulids. Some think that the proconsulids are the first apes. They have larger bodies, relatively larger brains, perhaps more flexibility in their shoulders, elbows, and hips, and no tail. Yet others argue that they are not true apes, but rather dental apes/derived catarrhines because they move as arboreal quadrupeds and climbers, hindlimbs longer than forelimbs, lateral scapula, a deep rib cage, and a pretty flexible spine. One species is proconsul.

Question 13

Afropithecus

Answer 13

Early Miocene: it is possible that later hominoids rose from Afropithecus. Another candidate for the earliest ape. Had a Proconsul-like body but teeth with thick enamel and stouter jaws. Hard object feeding.

Question 14

Middle Miocene

Question 15

Two species from the Middle Miocene

Answer 15

Kenyapithecus and Dryopithecus. They are considered definitive hominoids because they have relatively large brains, a dorsal scapula, less flexibility, broad shallow ribcages, no external tails, and longer arms than legs.

Question 16

Saadanius hijazensis

Answer 16

Late Eocene/Oligocene: Saadanius seems to have lived shortly before the common ancestor that gave rise to hominoids. Gives us the idea of the anatomical changes that may have been associated with this ancestor. Primitive features include projecting snout but had derived traits such as a tube-shaped ear canal.

Question 17

One species of the Late Miocene

Answer 17

Gigantopithecus: Homo erectus may have hunted Gigantopithecus, a huge 8-9 foot ape, to extinction.

Question 18

Late Miocene

Question 19

Anthropoids

Answer 19

Physical developments: orbital closure, increased reliance on vision, relatively larger brain, reduced snout, orbits positioned forward***Three key derived traits: fused frontal, fused mandible, orbital closure