The Fossil Hominids

A Journey from Australopithecus to genus Homo

Co. 2004 by Michael Spence. Revised 2006, 2007, 2010.

Part One:

The Australopithecines

Piltdown Man**FRAUD**

• “Discovered” in 1912 by Charles Dawson in Sussex, England

• Combination of…• Medieval human skull• Sawed-down orangutan

jaw• An elephant molar• A hippopotamus tooth• A canine tooth from a

chimpanzee fossil Third from left standing is Charles Dawson, wowing his colleagues in 1915. By 1953, the secret was out—FRAUD!

AUSTRALOPITHECUS– Word means “southern ape” due to its

discovery in South Africa

– All australopithecines were BIPEDAL

– Though each species is unique, they all share the following characteristics: small cranium, prognathism, large premolars and molars, small body size, and the possibility of being arboreal.

Australopithecus ramidus• A.k.a. Ardipithecus ramidus

b/c it’s too “ape-like” to be an australopithecine.

• Oldest, most primitive hominid so far (5 – 4.4 mya).

• Found 1994, in Awash Region in Afar (Aramis, Ethiopia).

• Largest canines of any hominid yet discovered—linked with the hominids due to the lack of a gap between the canine and the premolar on lower jaw like great apes.

New find: Published in October 2009: “Ardi” predates Lucy by over a million years (4.4 mya) as the oldest link to humans.

However, note the opposable big toe, large hands, and prognathic face, and ape-like pelvic region and legs indicating the species was not entirely bipedal.

Australopithecus anamensis• Found by Meave Leakey

(pictured) and Alan Walker 1994, Lake Turkana, Kenya.

• 4.2 – 3.9 mya.• Paltry fossil record: ten teeth

(not related), leg, arm, skull parts, jaw parts.

• Resembles a chimp; ramidus teeth (large canines).

• Leg bones suggest more upright and human-style walking.

• Arm bones suggest arboreal.

Australopithecus afarensis• First discovered in Hadar in the Afar Region, Ethiopia by Donald

Johanson in 1974. • He named the discovery ‘Lucy’ after the Beatles’ song “Lucy in the

Sky With Diamonds.” She dates to approx. 3.2 mya.• Afarensis accounts for most of the early hominid fossils found and

dates from 4 – 3 mya.• Smaller, yet pronounced canines and broad incisors resemble

chimp.• Definitely not arboreal, based on weight projections; but they

probably were good climbers.• More pronounced prognathism.• Brain case larger, but cranium has chimp features (broad at base).• Think fully erect, 3.5 – 5 foot tall bipedal chimp.

Donald Johanson• Schurz alum!• Graduated University of Chicago, 1974, with PhD in

Paleoanthropology• Besides Lucy, he is credited with over 20 distinct

afarensis and Homo habilis finds, has published hundreds of research articles and books, and gives yearly lecture and symposium talks throughout the world

• For a time, the chief rival of the Leakey family: Richard Leakey and Johanson are bitter enemies who refuse to debate one another’s finds!

• Established the Institute of Human Origins in the 1980s which is now centered at ASU

• Recently developed a new website: “Becoming Human”

This afarensis is the earliest known juvenile skeleton of a hominid yet found (3.3 mya)

Discovered in Hadar, Ethiopia in 2000 (research released 2006), not far from where Lucy was unearthed in 1974.

Dubbed as “Lucy’s Little Sister.”

Note the prognathic features of the skull, and the incisors and canines jutting outward as in the great apes.

Cranium is larger than chimps, but has its shape (again, the broad base)

Reconstructions of afarensis skulls: The “white areas” represent hypothetical projections based on the pieces found. Again note the large canines and incisors—more ape-like.

Laetoli Footprints• Discovered by Mary Leakey in Tanzania in 1975.• Dates back to 3.6 mya—footprints of afarensis• This 75-foot long trail resemble human feet:

heel, arch, and the big toe aligned with rest of toes.

• Supports that afarensis was bipedal, and perhaps fully land-based, i.e. not arboreal.

• The hominids that left these prints estimate around 4 – 5 feet tall based on their stride.

Close-up of foot: Note that the big toe is aligned with the rest of the toes, a human quality.

There is a pronounced heel and arch in this print based on the raised right side of the remains.

Australopithecus africanus

• First australopithecine to be discovered c. 1924 by Raymond Dart.

• 3.0 – 2.3 mya (latest data).• Cranium 10% larger than afarensis.• Less prognathism.• Larger premolars and molars. Less pronounced

canines.• Larger forelimbs (arms) than afarensis • Ape-like in body; human-like head.

“Taung Baby” of South AfricaFound in 1924 by Raymond Dart

3 – 5 years old at death, possible eagle or hawk attack victim.

One of the best examples ofA. africanus

Raymond Dart (1924) with his new discovery: Australopithecus africanus, the “southern ape.”

He thought it was the skull of a baby monkey, but further testing yielded an altogether new species, as well as new science.

Dart, being a pioneer in this infant field, was one of the proponents of the killer-ape-man hypothesis, which has since been discredited.

The two greatest pioneers of paleoanthropology: Raymond Dart and Louis Leakey, arguing into their twilight years over yet another fossil find

Recent x-rays and other computer scans indicate that Mrs. Ples might actually be Mr. Ples. Whatever the case may be, it represents the most complete specimen of africanus yet found

Another view of Mrs. (or Mr.)

Ples.

Discovered in 1947 in South

Africa.

It dates around 2.8 – 2.6 mya

The Robustine Australopithecines

• A. robustus and boisei overlap with genus homo.• Dated 2.3 – 1.3 mya. • Largest craniums of all australopithecines.• “Robust” jaw bones and large teeth set them apart from

rest of australopithecines.• Same size as africanus, but jaw bones and crania

suggest gorilla size head. • Sometimes referred to as “Paranthropus” to distinguish

from australopithecines.• Many suggest that these robustine hominids are an

offshoot of africanus whose line ended, with no one as a potential descendant

Australopithecus boisei

Dying out around 1.2 mya, boisei may be the last australopithecine to become extinct.

Australopithecus aethiopicus“The Black Skull”

Discovered in 1985 by Alan Walker.

It is called the “Black Skull” because the soil turned the bones black during fossilization.

Dated at 2.7 – 2.5 mya, it is the oldest robustine so far discovered and may be an ancestor to bosei and robustus

“Zinjanthropus” found by Mary Leakey and named by Louis Leakey 1959. A complete skull (the mandible has been reconstructed based on similar finds and projections

This find was classified later as a boisei.

Note the gorilla-like qualities of the cranium (crest), mandible (massive jaws), and the human-like teeth (large premolars and molars) which allowed them to eat hard nuts and seeds and rough plants.

Louis Leakey with a bosei jaw in one hand, a Homo habilis skull in his other, and a gorilla skull thrown in for good measure. His flamboyance, tenacity, and enthusiasm for his subject put paleoanthropology on the forefront of science. His lecture tours (which he gave up to his death) made paleoanthropology a respected field, rather than a “pseudo-science.”

He also kick-started the field of primatology by convincing and financing Jane Goodall, Dian Fossey, and Birute Galdikas to study chimpanzees, gorillas, and orangutans, respectively.

Louis Leakey: 1903 – 1972

He convinced most of the scholars of his day to hunt for man’s origins in Africa, not Asia.

Born and raised in Kenya by missionary parents, Louis was the subject of ridicule by his Oxford classmates who teased his bizarre accent and weird style of walking.

His lifestyle was shaped by his relation to the Kikuyu tribe, on which he wrote many anthropological theses.

His prolific research has always been contested, and he has often been proven wrong, but his contribution to the field is nothing less than legendary.

The Leakey elders in action c. 1960s.

Mary Leakey(1913 – 1996)

Worked and researched at Olduvai up until her death at the age of 83. She was the “brains” behind the dynamic duo of Louis and Mary—though Louis (at first) received most of the credit.

She discovered more than 25 distinctive fossil finds, 15 new animal species, and published hundreds of research articles and dozens of books (both scientific and autobiographical) she taught all her children the family business.

Quite the adventuress, she drank scotch and smoked heavy cigars nightly while reflecting on the day’s fossil hunting

Richard Leakey at his prime (comparing a robustine australopithecine with Homo ergaster. A high school drop-out, he quit school to conduct safaris in his homeland of Kenya. His most famous discovery is the near complete skeleton of “Turkana Boy” with Alan Walker (Homo ergaster), and has unearthed over 200 high quality fossil finds.

He lost both legs in a plane crash, and spends his time campaigning for wildlife conservation—predominantly on saving the elephants, and dabbles in the politics of his country (Kenya), rather dangerously and unsuccessfully.

Meave Leakey• Richard’s second wife continues to be a

prime contributor to her field and is seen as the new matriarch of the Leakey family

• Credited with the discovery of anamensis as well as Kenyanthropus platyops, which dates 3.5 – 3.2 mya and may be a precursor to afarensis as man’s earliest relative.

• Her daughter Louise, who completed her PhD in 2001, continues the family tradition

In 2003, Tim White (another colleague/rival claimed that the skull of Kenyanthropus (on the left) is too smashed and distorted to be considered as evidence for a valid species. Rather he claims it to be another example of afarensis (as seen on the right). You decide…