Early Anthropoids Lecture 4

Question 1

Name four anthropoid cranial traits

Answer 1

1) Fused frontal bones
2) Taller face
3) Fused mandibulae
4) Complete postorbital closure
5) No paraconids

Question 2

On the lower teeth, what have anthropoids lost that tarsiers still retain?

Answer 2

The paraconid.

Question 3

Why do the upper molars of anthropoids tend to be quite square?

Answer 3

Due to the development of a big hypocone and loss of paraconid

Question 4

The _______ and ______ are the same height in anthropoids.

Answer 4

The talonid and trigonid are the same height in anthropoids.

Question 5

The lingual cingulum is a ______ condition.

Answer 5

Lingual cingulum (with cusps in middle of tooth) is a primitive condition
Lost lingual cingulum with cusps nearer outside of tooth is derived.

Question 6

Describe the fossil /Anthrasimias gujaratensis/.

Answer 6

1) Same stratigraphic level as omomyids and adapids
2) Found in Cambay Basin in India
3) Approx. 54-55 mya in early Eocene
4) Potentially earliest anthropoid primate

So splitting events between tarsiers, streps, haps and anthropoids have already happened.
So their common ancestors would be from further back but we don’t have the fossils.

However, due to it being so close to the split, it is unclear if it is related to anthropoids.

Question 7

The closer you get to a _________ _______, the more similar the animals look so it’s difficult to tell if they’re different species.

Answer 7

The closer you get to a splitting event, the more similar the animals look so it’s difficult to tell if they’re different species.

Question 8

Describe Eosimias.

Answer 8

1) From the Eocene
2) Found in China
3) Small
4) Anthropoid similarities

Question 9

Name a difference between Eosimias and anthropoids.

Answer 9

The M3 talonid is much lower than the trigonid and it has a paraconid, unlike anthropoids (so if it is an anthropoid then it is a stem anthropoid)

Question 10

What is a stem group?

Answer 10

It has some but not all of the characteristics of the crown group

Question 11

Name a similarity between Eosimias and anthropoids.

Answer 11

They both have an indentation in the facet of the calcaneus.

Question 12

Describe Proteopithecus.

Answer 12

1) Late Eocene
2) Found at site L41 in Fayum
3) Three premolars
4) Some similarities to platyrrhines
5) 500g

Question 13

Describe Biretia.

Answer 13

1) Eocene
2) Fayum
3) Has really big orbits which suggests it was nocturnal, whereas most early anthropoids are diurnal.

Question 14

What traits does Biretia share with anthropoids.

Answer 14

Biretia has square-shaped molars and have lost paraconid and talonid and trigonid are pretty much the same height, (anthropoid traits).

Question 15

Describe Oligopithecines and name two of them.

Answer 15

Examples: Catopithecus and Oligopithecus

Traits:

1) Two premolars (synapomorphy with catarrhines? Can’t be catarrhine because they are crown anthropoids)
2) Has unfused mandibular symphysis (must be stem anthropoid)
3) Ectotympanic is ring-like and fused to the bulla like in platyrrhines

Question 16

Why is the loss of the P2 not a synapomorphy of anthropoids?

Answer 16

It has happened convergently in lots of species

Question 17

Describe Oligocene parapithecids and name two.

Answer 17

Parapithecus and Apidium are examples of Oligocene parapithecids.

Parapithecus had 3 premolars and no permanent incisors.

Apidium had 3 cusped upper premolars with 3 roots (anthropoids today have two roots)

Both have no paraconid and square looking molars.

Question 18

Describe parapithecid postcrania.

Answer 18

Tibia and fibula are closely approximated (not fused but close together) so it must have been doing quite a lot of leaping.

Question 19

What feature of Qatrania is anthropoid like?

Answer 19

Trigonid and talonid are the same height

Question 20

Describe Siamopithecus.

Answer 20

1) Eocene
2) Typically anthropoid teeth
2) Low rounded cusps –> probably eating a lot of fruit
3) Much larger body size (6-7kg)
4) From Thailand

Question 21

Name three anthropoid traits of Siamopithecus

Answer 21

1) Relatively short face (no snout)
2) Highly convergent and frontated orbits
3) Orbital rim lies well above the alveolar plane

Question 22

List three non-anthropoid traits of Eosimias

Answer 22

1) Unfused mandibular symphysis
2) P2 is single rooted not double rooted like in extant anthropoids but other stem anthropoids have this condition (Beard et al., 1996)
3) No hypocones in upper molars and they have paraconids

Question 23

List two anthropoid traits of Eosimias

Answer 23

1) Vertically implanted lower incisors

2) canine morphology similar to anthropoids