Primate Morphologies

Primate characteristics: Primates do not have a single characteristic that identifies them as being primates,
but rather they possess a number of traits, which are needed to classify them taxonomically.

Ø Primates have a large brain to body size ratio. The cerebral cortex is expanded in size so that in the more advanced primates it covers most of the brain. The olfactory area of the cortex has become reduced in
higher primates and the visual areas are expanded.

Ø Primates have forward facing eyes and stereoscopic vision. In all primates with the exception of
prosimians the eyes are in bony eye sockets and they see in color.

Ø Primates have reduced olfactory ability or sense of smell. The snout is generally reduced as well,
though there are some notable exceptions (baboons, mandrills & drills).

Ø The arm shows a higher degree of mobility (especially in apes) than other animals.

Ø All primates have a clavicle that provides support for the shoulder.

Ø The lower arm has two separate bones, the radius and ulna. These bones allow the forearm to be rotated
180 degrees.

Ø The primate hand generally retains the primitive condition of having five digits, pentadactyly. This characteristic contributes to the prehensility (grasping ability) of both hands and feet of most primates.

Ø Primates tend to have nails and tactile pads on the ends of their fingers. Exceptions include toilet
claws in prosimians and the claws in Callitrichidae.

Ø Most primates (all anthropoids) have a hemochorial placentas. These types of placentas are more
efficient in the transmission of nutrients, in that the nutrients need only cross a single placental
barrier.

Ø Primates generally have single births. Marmosets, Tamarins and some prosimians are exceptions
to this rule.

Ø Primates tend to have long infant dependency periods where learned behaviors become increasingly
more important for survival. Parents tend to invest more heavily in each infant’s survival than in other comparably sized mammals.

Prosimian characteristics:

Lemuridae, & Indriidae Families (The family Daubentoniidae is not included below)

Ø Bony eye rings are present and bony eye sockets are absent in all lemurs.

Ø Tapetum (reflective surface on the retina).

Ø Mobile ears

Ø Rhinarium, Jacobsen’s organ, and elongated nasal area

Ø Upper lip is tightly attached to the gum by the frenulum, resulting in a nearly expressionless face.

Ø Special scent glands may be found on the wrists, buttocks and armpits.

Ø A “dental comb” consisting of procumbent lower incisors and canines is present.

Ø Toilet claw is found on the second toe. Nails are present on all other digits.

Ø Epitheliochoral placenta with its twin barriers is present.

Ø Mandible (jaw) and frontal bone composed of two separate bones each.

Ø Tactile vibrissae (whiskers) are present

Ø The Dental formula for most lemurs is 2 x 2133/2133

Family Lorisidae (slinder loris, slow loris, potto,

Ø The characteristics of Lorisidae are very similar to Lemuridae with the following changes.

Ø The Loris lacks a long index finger on each hand. The wrists and ankles have special capillary
networks (retia mirabilia) that permit the Loris to hang from branches for long periods of time.

Ø Galaginae, Bush Babies, have a lower limb adaptation for jumping.

Tarsioidea

Family Tarsiidae

Ø Very large eyes with nonfunctional eye muscles. Each eye outweighs the brain. The head may
rotate nearly back to either side 170 degrees.

Ø The eye is enclosed in a nearly complete bony eye socket.

Ø There is no rhinarium.

Ø Anklebones are elongated and the tibia and fibula are fused. This permits their vertical clinging
and leaping locomotor pattern.

Ø Two toilet claws are present on each hind foot instead of the normal one for prosimians.

Ø Tarsiers lack dental combs and their molars are triangular with three tall cusps.

Ø Tarsiers are generally nocturnal predators.

Suborder Anthropoidea Infraorder Platyrrhini Superfamily Ceboidea

NEW WORLD MONKEYS

Ø Complete bony eye socket

Ø Platyrrhine nose, with thick nasal septum and nostrils facing out to the sides.

Ø Mandible (jaw) and frontal bone are each one bone.

Ø Reduced or absent frenulum

Ø No prominent whiskers (tactile vibrissae)

Ø No dental combs

Ø No rhinarium or Jacobsen’s Organ.

The Family Cebidae Including Pithecinae (sakis,& uakaris); Callicebinae (Titi monkeys);
Atelinae (Howler monkeys, Spider monkeys & Woolly monkeys); Cibinae (Capuchin monkeys
& Squirrel monkeys)

Ø Nails are present on all fingers and toes.

Ø The degree of thumb opposability is varied, ranging from no opposability to a near precision grip.

Ø Some members of Cebidae have prehensile tails.

Ø Single births are the rule for cebids.

Ø All cebids are generally arboreal quadrupeds.

Ø The dental formula for cebids is 2x 2133/2133

The Family Callitrichidae Includes the genera Callithrix & Cebuella ((Marmosets) and Saguinus & Leontopithecus (Tamarins)

Ø They have claw-like nails on all fingers and toes except on the great toe that has a nail.

Ø Twin births are the rule for these primates.

Ø The dental formula is 2x 2132/2132 and the molars are triangular shaped.

Ø The shape of the lower anterior teeth, canines and incisors, helps to place a member of Callitrichidae
into either the marmosets or the tamarins. In general, marmosets have larger broader lower incisors
that are about the same height as the lower canines. Tamiarins tend to have smaller narrower lower
incisors and canines that are much taller than the incisors.

Ø These are primarily arboreal animals of extremely small body size. Squirrels are of the approximate
same size.

Infraorder Catarrhini

Superfamily Cercopitheciodea

OLD WORLD MONKEYS

Ø Eyes are in complete bony eye sockets.

Ø There is frequent and considerable sexual dimorphism in both canine size and body size.

Ø Ischial callosites are present on the buttocks of these old world monkeys

Ø Sectorial premolars are present in many of these primates. These teeth provide shear surfaces for
the canine teeth to cut against.

Ø Molars are rectangular with four cusps, and are described as bilophodont.

Ø In the ear there is a bony tube that extends from the tympanic membrane to the external ear. New
World monkeys and prosimians lack this feature.

Ø Old World monkeys tend to have greater brain to body size ratios

Ø Old World monkeys tend to have larger body weights than New World monkeys.

Ø Old World monkeys tend to spend more time on the ground than New World monkeys.

Ø Mandible is composed of one bone as is the frontal bone

Ø Reduced or absent frenulum

Ø Lack whiskers, tactile vibrissae

Ø Cerebral cortex includes a central sulcus.

Ø The dental formula is 2x 2123/2123

Family Cercopithecidae Subfamily Cercopithecinae, the cheek pouch monkeys. Including the (macaques, mangabeys, baboons, mandrills, drills, & guenons)

Ø The thumb is more frequently opposable

Ø Cheek pouches are present for food (short-term food storage).

Ø Old World monkeys tend to live in complex social groups.

Ø The molars tend to have high crowns and low cusps to aid in grinding.

Ø Incisors tend to be broad and well suited to cutting fruits.

Ø All four legs tend to be nearly equal in length. This helps in quadrupedal locomotion, but does not
promote jumping as much as having longer hind limbs.

Family Cercopithecidae Subfamily Colobinae the leaf eating monkeys (Colobus monkeys & Langurs)

Ø These monkeys do not have cheek pouches.

Ø Molars have low crowns and high cusps that add in shearing leafy material.

Ø Incisors tend to be narrow and are not as extensively used in food processing.

Ø These monkeys do have sacculated stomachs. Sacculated stomachs allow these primates to eat a diet
with lots of leaves.

Ø Some have reduced thumbs and elongated hind legs.

Infraorder Catarrhini Superfamily Hominoidea

Families Panidae (gorillas & chimpanzees), Pongidae (Orangutans), and Hylobatidae (gibbons and
siamangs)

APES

Ø Apes have orthograde (upright) posture.

Ø Apes have dorso-ventrally flattened chests.

Ø Scapula is located on the back of the chest and the shoulder joint has great freedom of motion.

Ø All apes have at least limited suspensory locomotor ability. These means they are all capable, at least,
limited semi-brachiation or brachiation.

Ø Apes lack tails.

Ø Hominoids have longer arms than legs. (Humans are an exception)

Ø Apes have the Y-five molar cusp pattern on their lower molars.

Ø The dental formula is