Lecture 9 Flashcards
what is the Geologic Time Scale
The GTS is a standard division of Earth history into eons, eras, periods and epochs based on large-scale geological events
what is important about New Research: Fossilized Angiosperms
Two 15-‐million-‐year-‐old,extinct Strychnos flowers have been found preserved in fossilized amber fragments from the Dominican Republic
wha are the types of Proto-Primates
Purgatorius (genus)
Plesiadapiformes (order)
what are Purgatorius
Purgatorius fossils date to the K-‐T boundary: 66 - 63 mya.
Small, rodent-like mammals, known from only a few fossilized teeth and ankle bones.
Likely insectivorous, possibly frugivorous.
Ankle morphology indicates grasping abilities; thus, likely arboreal
what are Plesiadapiformes
Parallel or ancestral to modern Primates.
Appeared during the Paleocene (65-55 mya)
Like modern Strepsirrhines, they were quadrapedal, nocturnal, arboreal, largely reliant on smell and able to leap from branch to branch.
Unlike all primates, however, they lacked either a postorbital bar or closure. In addition, they had monocular vision, claws instead of nails and relatively small brains
The earliest true primates appear when
during the early Eocene (55 and 34 mya) in Africa, Europe, Asia and North America
The two families of these first primates exhibit
grasping hands and feet binocular/stereoscopic vision nails instead of claws a post-orbital bar increased brain size
what were the Miocene Monkeys
New World monkeys appear in South America by 23 mya (during the Miocene)
Around 2 mya, these Platyrrhines spread through the Caribbean.
The Platyrrhines are generally believed to have originated in Africa; how they traversed 2000 miles of open water remains a mystery
what were the Miocene Apes
True apes are far less abundant than prosimians or monkeys in the fossil record. This reflects either their scarcity in life, or the effects of taphonomy.
The first true apes begin to appear during the early Miocene epoch, around 25 mya
Their remains have been recovered from East and Central Africa, Europe, Central Asia and Southeast Asia.
what were the Miocene Apes Proconsul (genus) like
The earliest known fossil apes are of the diverse genus Proconsul.
Several species of Proconsul have been discovered. The smallest weighed between 20 and 26 lbs.; the largest weighed as much as 150-200 lbs. All were arboreal quadrupeds.
They exhibited an unusual mix of monkey and ape traits:
Ape-like skull and teeth
Monkey like post-cranium
what were the Miocene Apes Kenyapithecus (genus) like
Kenyapithecus was a genus of arboreal quadrupeds known largely from dental remains.
Fossils resembling Kenyapithecus dating to around 14 mya have been found in Turkey, strongly indicating it was one of the first Miocene apes to begin migrating from East Africa to Eurasia
what were the Miocene Apes Dryopithecus (genus) like
Fossil remains of the Dryopithecus genus have been found across Europe.
Species ranged in weight from between 33 and 100 lbs.
Arboreal and quadrupedal, they may have moved via quadrumanous locomotion.
They share numerous traits associated with modern apes, including long arms and strong grasping hands
what is interesting about Miocene Apes
One of many unresolved issues in paleoanthropology is the unclear ancestry of today’s African great apes. No chimp/bonobo or gorilla fossils have been found post-dating their respective divergences from our ancestral line
what is the Upper Miocene Fossil Gap (Miocene Apes)
12 – 6 mya, very few fossil bearing deposits in Africa
when did our evolutionary line diverged from that of the Miocene apes
It is clear that between 6 and 8 mya, our evolutionary line diverged from that of the Miocene apes. The resulting line of hominins began spreading rapidly throughout East and Southern Africa
what are the differences between apes and hominins
our evolutionary line diverged from that of the Miocene apes
when did the Sahelanthropus tchadensis live
6-7 mya
describe Sahelanthropus tchadensis
in 2002, a French team, led by Michel Brunet, discovered a nearly-complete, but distorted fossilized cranium in north-central Chad.
Nicknamed “Toumaï,” the specimen was clearly a primate, and had an unusual combination of ape and hominin characteristics.
If Toumaï is a hominin, he* would be the earliest yet recorded
Today a desert, the Sahel region was once a densely forested environment, long thought geographically removed from the center of hominin evolution in East Africa.
When first described, the classification of Sahelanthropus as a hominin was criticized as premature. Today, however, the consensus is that he was likely an obligate biped, and therefore, a hominin
when did Orrorin tuganensis exist
6.1-5.7 mya
describe Orrorin tuganensis
Orrorin tuganensis is represented by around 20 fossilized teeth and long bone fragments.
Orrorin’s teeth are chimp-like; however, its femora are notable for the length and shape of their necks, which are like those of humans and bipedal hominins.
There is no consensus on Orrorin’s status as a hominin; this will likely remain unchanged until cranial elements are discovered
when did Ardipithecus kadabba exist
5.8-5.2 mya
describe Ardipithecus kadabba
Ardi means “ground/floor“ in Afar; pithecus from Greek for “Ape”; kadabba Afar for “oldest ancestor”
Ardipithecus kadabba is known from only from a number of chimp-like teeth andsomepost-cranial bone fragments, none of which are diagnostic, with the exception of a single, mostly-complete toe bone (phalanx), which hints at bipedal locomotion
when did Ardipithecus ramidus exist
4.4 mya
describe Ardipithecus ramidus
Ardipithecus ramidus is, like its sister species, Ar. kadabba, found in the Middle Awash region of Ethiopia. However, much more is known about this species, which postdates Ar. kadabba by around one million years.
More than 15 years of field and laboratory work by Tim White and others have reconstructed a remarkably complete skeleton of this species. As a result, we know more about Ar. ramidus than we do about many more recent hominins
describe the traits of “Ardi”
“Ardi” is believed to be a female. She stood approximately 4 feet tall and weighed around 120 lbs. Her dental arcade is U-shaped, an ape characteristic; however, her canine teeth are distinctly more human-like than those of her sister species, Ar. kadabba.
Information about the local paleoenvironment in the Middle Awash region indicates Ardi lived in a densely forested area. However, given the relatively short length of her arms (when compared with apes), she likely spent much of her time on the ground.
She had an opposable big toe, but the rest of the foot is human-like:
rigid and suited for walking upright
Features of the pelvis also indicate Ardi was an obligate biped. Bilateral symmetry is assumed in pelvis bones.
Thus scans were taken of the only somewhat-complete bone, allowing the
entire pelvis to be reconstructed.
The result showed a bowl- shaped pelvis, similar to later bipedal hominins and humans
