Chapter 8 Flashcards
Radiations
this population might evolve independently into a new species, changing to fit particular ecological niches in the new environment and never requiring natural selection to complete its reproductive isolation from the parent species.
Plesiadapiforms
archaic primates
Euprimates
true primates
Anthropoids
monkeys and apes
Old World
Africa
What are some of the factors that lead to primate diversity and evolution?
Climate change forced major extinctions as the northern continents became increasingly dry, cold, and seasonal and as tropical rainforests gave way to deciduous forests, woodlands, and eventually grasslands.
Diagnosis
The features that allow you to recognize a group
St. George Jackson Mivart
British naturalist who figured out what pattern every primate has that makes it a primate: nails, clavicles, placentation, orbits encircled by bone, three tooth types i.e., incisors, canines, premolars/molars), posterior lobe of the brain, calcarine fissure of the brain, opposable thumb and/or big toe, nail on the big toe, well-developed cecum, pendulous penis, testes within a scrotum, and two nipples in the pectoral region
Le Gros Clark
Expanded on St. George’s theory. Clark’s trends emphasize the flexibility and generalized nature of the limbs, mobility and dexterity of the digits, reduction of the snout with elaboration of the visual system, retention of simple teeth, and elaboration of the brain with prolonged period of juvenile dependence
Robert Martin
Expanded on both of their theories and emphasized distinctive reproductive characteristics of primates, along with details of cranial anatomy and grasping extremities
What are challenges in determining if a particular animal is a primate?
From the first modern attempts to classify primates, scientists have struggled to come up with traits that are possessed exclusively and universally by primates. In the end, most have generated lists of traits that are of variable utility in making a correct diagnosis.
Why are some of the traits Mivart decided on problematic?
Many primatologists have pointed out that no single feature on this list is unique to primates. Also, nails appear twice. Taken together, perhaps it is a useful list. Unfortunately, some of these traits e.g., three types of teeth) are neither clear nor true of all primates. Other traits, like nipple number and location, are quite variable among primates. Still others, for example the pendulousness of the penis, can be assessed in only males
What makes primates unique?
Instead, if there is something unique about primates, it is probably a group of features rather than one single thing
Frederic Wood Jones
credited with the Arboreal Hypothesis of primate origins which holds that many of the features of primates evolved to improve locomotion in the trees
What features do primate have that make moving through trees possible?
the grasping hands and feet of primates are well suited to gripping tree branches of various sizes and our flexible joints are good for reorienting the extremities in many different ways.
Matt Cartmill
studied and tested the idea that the characteristic features of primates evolved in the context of arboreal locomotion.
How does Cartmill’s theory differ from Jones’?
jones-> improve locomotion
Carmill->studied the evolution of primates in the context of arboreal evolution
Why did Cartmill begin to question Jones’ theory and what does he believe drove primate evolution?
Cartmill reasoned that there must be some other explanation for the unique traits of primates because other animals can climb trees without primate traits. His hypothesis emphasizes the primary role of vision in prey detection and capture; it is explicitly comparative, relying on form function relationships in other mammals and nonmammalian vertebrates. According to Cartmill, many of the key features of primates evolved for preying on insects in this special manner.
Robert Sussman
argued that the few primates that eat mostly insects often catch their prey on the ground rather than in the fine branches of trees. Furthermore, predatory primates often use their ears more than their eyes to detect prey. Finally, most early primate fossils show signs of having been omnivorous rather than insectivorous. Instead, he argued, the earliest primates were probably seeking frui
Paleocene
distinctive visual traits and extremities in the Paleocene approximately 65 million to 54 million years ago
Why some anthropologists unhappy with Cartmill’s visual predation hypothesis?
One reason for this is that many primates today are not especially predatory. Another is that, whereas primates do seem well adapted to moving around in the smallest, terminal branches of trees, insects are not necessarily easier to find there.
Eocene
Subsequent to the paleocene. Eocene approximately 54 million to 34 million years ago) just when angiosperms (flowering plants) were going through a revolution of their own
Diffuse coevolution
coevolution
D. Tab Rasmussen
noted several parallel traits in primates and the South American woolly opossum, Caluromy. He argued that early primates were probably foraging on both fruits and insects.
Mesozoic Era
Placental mammals, including primates, originated in the Mesozoic Era approximately 251 million to 65.5 million years ago), the Age of Dinosaurs. During this time, most placental mammals were small, probably nocturnal, and probably avoided predators via camouflage and slow, quiet movement
Cretaceous Period
The extinction of the dinosaurs and many other organisms) at the end of the Cretaceous Period approximately 145.5–65.5 million years ago) might have opened up these ecological niches
Tertiary Period
leading to the increased diversity and disparity in mammals of the Tertiary Period
approximately 65.5–2.5 million years ago).
Paleocene
The Paleocene was the first epoch in the Age of Mammals
Eocene
Many of these groups achieved a broad range of sizes and lifestyles as well as a great number of species before declining sometime in the Eocene or soon thereafter)
How did the presence of dinosaurs (and their later extinction) affect mammals?
Describe when mammals began to flourish. Name epochs and explain reasons why modern placental mammals began to dominate the earth.
Tertiary Period. The extinction of the dinosaurs at the end of the Cretaceous Period might have opened up these ecological niches, leading to the increased diversity and disparity in mammals.
Euprimates
trie primates
Haplorhines
septum in haplorrhines
Auditory bulla
is a hollow bony structure on the ventral, posterior portion of the skull that encloses parts of the middle and inner ear
Petrous bone
Petrous portion of the temporal bone. It houses the inner ear apparatus, among other things
How do plesiadapiforms differ significantly from modern primates?
Plesiadapiforms are archaic primates, meaning that they possessed some primate features and lacked others
Purgatorius
the earliest primate
What about the purgatorius led anthropologists to believe it was a primate?
This Paleocene mammal is known for teeth that are very primitive for a primate
Where did they live?
western North America and western Europe
Diastema
resulting formation of a rodent.
Space between adjacent teeth
Convergent evolution
The independent evolution of a morphological feature in animals not closely related e.g., wings in birds and bats
Plagiaulacoid
Dental condition where at least one of the lower cheek-teeth molars or premolars) is a laterally compressed blade
Discuss what we know about the morphology of plesiadapiforms. Make sure to include a discussion of teeth.
Most plesiadapiforms were small, the largest being about three kilograms. They had small brains and fairly large snouts, with variable eye size. Most plesiadapiforms have large incisors
relative to the molars and in some species, the lower incisors usually one pair) are reminiscent of long daggers or spears. the upper central incisors are also very unusual, with small cuspules spaced out like fingers, having some unknown function perhaps related to seizing or cropping food.
What is interesting and unusual about Carpolestidae?
This family contains three major genera and a few minor ones. They are almost exclusively from North America with a couple of possible members from Asia), and mainly from the Middle and Late Paleocene. Plagiaulacoid teeth.
Where did Carpolestidae live and in what kind of habitat? What did they eat?
They are almost exclusively from North America with a couple of possible members from Asia. Would probably be most useful in processing food items of combined textures, particularly a soft interior covered by either a brittle or ductile coat, which are characteristic of an omnivorous diet composed of invertebrates, nuts, and seeds
Stem
Taxa are basal to a given crown group but are more closely related to the crown group than to the closest living sister taxon of the crown group
Summarize why some anthropologists wanted to remove plesiadapiforms from the order Primate.
The debate about the status of plesiadapiforms continues, owing to a persistent lack of key bones in some species and owing to genuine complexity of the anatomical traits involved
What changed those anthropologists’ minds more recently?
New and more complete specimens demonstrate that the postcranial skeletons of plesiadapiforms, including the hands and feet, were primate-like, not dermorpteran-like. New fine-grained CT scans of relatively complete plesiadapiform skulls revealed that they share some key traits with primates to the exclusion of other placental mammals
Adapoida
Order: Primates. One of the earliest groups of euprimates true primates; earliest records from the early Eocene)
Omomyoidea
Order: Primates; Superfamily: Omomyoidea. One of the earliest groups of euprimates true primates;
earliest record in the early Eocene).
Where did adapoida and omomyoidea live?
where they are present in western North America, western Europe, and India
In what era?
Eocene
What likely contributed to their extinction?
Oligocene extinctions, when colder temperatures, increased seasonality, and the retreat of rainforests to lower latitudes led to changes in mammalian biogeography
Adapoids
several dozen extinct species of primates of the suborder
Family adapidea
family of extinct primates
Notharctidae
western North America species
Antius
Smilodectes
What features do adapoids have that leads anthropologists to conclude they are primates?
Anthropologists believe adapoids were diurnal herbivores whose sexual pattern was polygyny. Why did anthropologists conclude this?
How do anthropologists know about adapoids? What were some challenges in gathering fossils and skeletons?
Briefly describe the major adapoids, where they were found and what traits they had.
Microchoeridae
Necrolemur
Amomyidea
Anaptomorphinae
Omomyinae
Thilhardina
