|Examples of several primate families|
Primates are an order which includes haplorrhines and strepsirrhines. The first primate species appeared during the Paleocene epoch. Molecular studies support the hypothesis that primates appeared during the latter part of the cretaceous. Primates are divided into two suborders, Strepsirrhini and Haplorrhini.
Strepsirrhines are found in a lesser diversity then haplorrhines, with their biodiversity mostly situated in Madagascar and South America. All members are lemuriforms, during the Eocene glaciations they had managed to arrive on South America by rafting on floating mats of vegetation, and they had radiated due to the lack of haplorrhines. A majority of the lemuriforms are nocturnal and have large orbitals and a small brain volume in comparison to haplorrhines. Some have a long femur and multiple curves in their spine, in order to absorb the pressure produced when jumping branch to branch, while the galagos are nocturnal critters that compete with other primates in mainland Africa, and contain only several species. The lack of simians in this timeline meant that much of their diversity was kept, however the prosimians were still devastated by the early diversification of grass in this timeline.
In contrast, haplorrhines are very diverse, inhabiting the all Holarctic continents. Unlike our haplorrhines they retain a rhinarium, however the adults possess a fleshy bit of muscle between the rhinarium and the mouth, which is thought to be a primitive form of an upper lip. They lack the vitamin C-synthesizing enzyme that strephsirrhines have, meaning they have to obtain their own vitamin-C through ingesting food. It has a single suborder, Tarsiiformes, which include the crown group primate family Omomyidae. Omomyids are basal tarsiiformes and have a shortened rostrum, enlarged orbitals (in some species), a vomeronasal organ, they lack anterior molars. Omomyids are relatively diverse, filling various niches throughout most of Asia (with the exception of various archipelagos and India). The other family are the false tarsiers, of the family Opotarsiidae, which have some adaptations akin to some lemuriforms, and are nocturnal critters feeding mostly on fruits, small animals and insects. Eosimiidae is the other family, thriving in India and spreaded east.
One of the only few haplorrhines which actually lack a rhinarium, they are far less specialized then their relatives and had radiated in India, and during the early Oligocene, spreading east and replacing a majority of all omomyids and opotarsids that share similar niches. Their thumbs are opposable, and are covered by epidermal ridges to help grip. The cranium has increased in size considerably. Their dentition is quite primitive in contrast to other specialized mammals, however the canines have been reduced and their comb-like incisors, found in most other primate species, are completely absent. And like most other mammals the teeth are shed only twice, and the teeth retained during maturity are coated with a thick layer of enamel, which strengthens the teeth. The nails on their index finger are replaced by claws, while in typical species their head could move a hundred-eighty degrees.
Simiaethon are tiny, their length and weight is on average, six inches, and a hundred grams. The upper incisors are separated and solely used for grooming. The tarsus, or the ankle bones are lengthy, and the hallux is opposable, and is the center of gravity. Simiaethon escape competition with omomyids by becoming diurnal. The tail is short and stumpy, and the frontal part of the tail fused into a coccyx. Simiaethon are characterized by their distinctive tawny pelt, and, rodent-like appearance, a perfect example of evolutionary convergence. They instinctively rub their pelts with mud in order to camouflage themselves.
Simiaethon contains sixteen species, all of which are optimistic omnivores, with the exception of one. This species (Simiaethon minimus) feeds primarily on nectar; the tongue is broad and all its teeth are reduced, except for its upper incisors. The sugar-rich diet of nectar bolsters the metabolism of the animal. Simiaethon are polygamous, the females live in complex social groups consisting of juveniles and mothers while the adult males are solitary, urinating near the female groups in order to lure them. Males make a nest from twigs and decorate them with flowers, and a female that is in courtship leaves the group. Estrus happens in early spring, and males will mate with all the females he courts before the females leave once again to their respective groups. Due to their small body the pregnancies are quite short, around two months.
Opopan resemble superficially like the proori, minus the short femur. The prehensile tail is relatively long and is tipped with rough epidermal ridges in three species. The premolars are blade-like, and they are arboreal, feeding primarily on fruits, they can grip on branches and twigs by applying saliva to their palms and fingertips, which prunes them. Unlike the proori its limbs are all the same size, and the spine has not developed multiple curves yet. The thumb is opposable, and the index fingers and the thumb bare no nails, instead it is replaced by claws that curve inwards. Their diet is grass, which they digest by storing grass in their cecum for long periods of time, and the bacteria ferments it. The molars’ crowns are more prominent, and they perform a process similar to ruminating, which they vomit out their food a few hours after ingestion.
Opopans’ pelt is black, and in older individuals, their back is gray with age. They live in herds numbering a few dozen, which is led by the elder. The younger individuals share a strong bond with the elders, taking parasites from the elders’ pelt. Opopans are monogamous; they cooperate with their mate to raise their offspring.
Sivasimia diverged earlier from the main evolutionary line. The zygomatic arch has fused with the dermal cells, resulting in a hard, bony covering at the cheeks. Hair follicles can be raised and the veins inside the cheeks will engorge (similar to blushing) if threatened. Sivasimia possess a paler, ghostly pelt, streaked with darker stripes; it’s a thermoregulation system, the pale areas reflect light while the dark areas absorb heat, it is also used to break their outline. The tail is packed with chevrons, which enables them to stand on it. Sivasimia also has the most bizarre diet; instead of being frugivorous or graminivorous, they are scavengers, feeding off the scraps from arboreal raptors.
Sivasimia behave more like predators, urinating to mark their territory, only allowing other individuals to cross during the mating season, which is in winter. Only the strongest of the males survive this harsh and stressful season period of time, were the stresses of the rut often leave males worn out.
Amphilemuriforma is a genus that includes proori, and two species of gliders that are regarded as the basal representatives of the genus. The two latter species within this genus possess a unique ability, the ability to glide. A patagium is spread from frontal to rear limb. This membrane lacks hair to reduce drag, and instead of protecting it with a thick pelt, the patagium instead, retains little nerve endings to numb itself, but this also reduced sensitivity to changes in the outside environment. The tail vertebra is surrounded with muscles associated with steering an individual while gliding. The snout is also streamlined and most of its weight is situated on the torso, probably to accelerate the gliding process. Paramphilemur are in contrast to most other primate species, monogamous and give birth to multiple off-springs after a gestation rate of nine months. The males have been observed performing some kind of mating ritual, rubbing its pelt with nectar and other fluids and giving flowers to females. Through reproduction, a couple could produce a herd of juveniles numbering fifteen in a period of five years together. Its unique ability and its fast reproduction rates mean that they are one of the most common animals in the forest.
Evolving at the middle Eocene, the family once spanned all over the lower latitudes a majority of its genera went extinct in Africa and Asia during the Oligocene. They are the smallest primates known, slightly smaller than the marmoset. The last representatives are in India, and some archipelagos in South East Asia. They resemble prosimians, and evolve some traits convergently. The traits include a smaller cranium (however their brain to body ratio are quite high, but this it usual for smaller animals) and larger orbitals, which reflects their lifestyle; they are nocturnal in order to escape competition from other primates. The pubic bone has fused together and their spine has developed multiple curves in order to absorb force, both adaptations for leaping. The femur is also quite long, and their eyes had redeveloped the ability to see three wavelengths, by redeveloping a color photopigment that can sense other wavelengths. The reason for this is to avoid confusion on the branch that they are hopping to, which is an advantage in the dense, multicolored rainforest.
They are the earliest crown group primate clade, evolving in the Paleocene and radiating in the Eocene epoch, before declining in the early Miocene epoch, a single group thrived and those are the terrestrial omomyids, living in the plains of China. They are certainly advance in comparison to their prosimian relatives and have the highest skull volume of any known primate and have the highest brain-to body ratio than any large mammal. The rostrum and other nasal bones are reduced, and they lack anterior molars. Their cheek teeth are adapted to either feed on insects or fruits, and the nectarous species possess a long prehensile tongue used for lapping up nectar from flowers and honey. The tail vertebra has been reduced to a coccyx and it is attached with muscles necessary for expelling feces. There are cavities and canals leading to a vomeronasal organ, and the tongue is either forked or is very broad. The tongue captures pheromones, chemical messengers that contain information.
Most species are arboreal, brachiating or walking through branches and twigs. They possess an evolutionary advantage, blood engorges the fingertips, and the dead epidermal cells pile up on each other. This process is called pruning, and it improves grip. Both the tibia and femur are short and broad, indicating they do not leap frequently; instead it is surrounded by muscles for easy consolation during locomotion. Omomyids still lack the characteristics of opotarsiids; for example, the fusing of the fibula and the tibia into one and the fusing of pubic bones, which leads to most biologists to consider that omomyids are primitive and diverged from the main tarsiiform evolutionary line early.