3. Sahelanthropus tchadensis • Unveiled July 10, 2002 • Toros-Menalla locality, Djurab Desert, northern Chad, central Africa • Fauna includes aquatic and amphibious animals along side gallery forest and savanna fauna – Fish, crocodiles, primates, rodents, elephants, equids, bovids • Suggests hominid lived close to a lake, but not far from a sandy desert • Biochronology suggests an age between 6 and 7 million years

4. Sahelanthropus tchadensis

5. Orrorin tugenensis This species was named in July 2001 from fossils discovered in western Kenya (Senut et al. 2001). The fossils include fragmentary arm and thigh bones, lower jaws, and teeth and were discovered in deposits that are about 6 million years old. The limb bones are about 1.5 times larger than those of Lucy, and suggest that it was about the size of a female chimpanzee. Its finders have claimed that Orrorin was a human ancestor adapted to both bipedality and tree climbing, and that the australopithecines are an extinct offshoot. Given the fragmentary nature of the remains, other scientists have been skeptical of these claims so far (Aiello and Collard 2001). A later paper (Galik et al. 2004) has found further evidence of bipedality in the fossil femur.

6. Orrorin tugenensis

7. LT 329: Lothagam • Dating is set at 5.8 – 5.6 mya • Jaw fragment shows numerous features reflecting improved power and efficiency in molar grinding – Cannot be distinguished from later Pliocene australopithecines including A. afarensis (Kramer) and A. ramidus (White

9. Ardipithecus ramidus kadabba • Discovered at Aramis, Ethiopia • Announced in July 2001 • Dated at 5.2 – 5.8 million years • Several jaw and bone fragments – Toe bone resembles A. afarensis , suggesting bipedality

10. Ardipithecus ramidus kadabba

11. Ardipithecus ramidus ramidus • Discovered at Aramis, Ethiopia • Announced in September 1994 • Dated at 4.4 million years • Remains consist of skull and jaw fragments. • Other fossils found with it indicate that it may have been a forest dweller • Teeth are intermediate between those of earlier apes and A. afarensis , but one baby tooth is very primitive, resembling a chimpanzee – Thin enamel on the molars • Undescribed remains suggest bipedalism – Foramen magnum positioned forward – Humerus does not appear to be weight bearing – Limestone encased partial skeleton suggests bipedality

12. Ardipithecus ramidus

13. New Controversy • For over a century we have expected fossils to look more and more ape-like as we approach the common ancestor with chimps • Recently a number of the features that have been assumed to be derived associated with the face and teeth are being re-evaluated – We’re beginning to think that the common ancestor looked more hominid than ape-like in these features, making it more difficult to tell when we have a very early hominid like Sahelanthropus or Orrorin

14. 6-8 Million yrs Ago Modern African Apes Modern Humans More Ape like More Human like Common Ancestor Original Model

15. 6-8 Million yrs Ago Modern African Apes Modern Humans More Ape like More Human like Common Ancestor New Ideas

16. Australopithecus anamensis

17. Australopithecus anamensis • Named in August 1995 • Material consists of 9 fossils from Kanapoi in Kenya and 12 fossils from Allia Bay in Kenya • Aged between 4.2 and 3.9 million years ago • Mixture of primitive features in the skull, and advanced features in the body • Teeth are a mix of features – Hominid thick enamel on molars – Ape-like sectorial lower first premolar – Relatively large canines • Tibia suggests bipedality • Humerus is extremely hominid in form

18. Australopithecus afarensis

19. Australopithecus afarensis • Aged between 3.9 and 3.0 million years ago • Apelike face with a low forehead, a bony ridge over the eyes, a flat nose, and no chin • Cranial capacity from 375 to 500 cc – Within chimp range, 1/4 - 1/3 modern humans • Pelvis and leg bones far more closely resemble those of modern man, and leave no doubt that they were bipedal

20. Australopithecus afarensis Lucy: 40% complete skeleton

21. • Laetoli footprints • Discovered by Mary Leakey • Volcanic tuff dated at almost 3.5 million years • Upright, bipedal locomotion of two or three hominids

22. Kenyapithecus platyops • From the site of Lomekwi, western side of Lake Turkana in northern Kenya, named in 2001 • More than 30 skull and dental fragments – Two have been assigned to K. platyops – Other fragments not yet assigned to any genus or species • Found in deposits reliably dated to between 3.5 million and 3.2 million years ago • Other mammalian species found at Lomekwi suggest that the site was part of a complex mixture of grassland and wooded habitats – Like other roughly contemporary sites such as Laetoli (Tanzania) and Hadar (Ethiopia), where remains of A. afarensis have been found

23. Kenyapithecus platyops Holotype KNM-WT 40000 a, left lateral view (markers indicate the plane separating the distorted neurocranium and the well-preserved face). b, Superior view. c, Anterior view. d, Occlusal view of palate. Paratype KNM-WT 38350. e, Lateral view. KNM-WT 40001. f, Lateral view. g, Inferior view. Scale bars: a–c, 3 cm; d–g, 1 cm. (Leakey et al. 2001)

24. KNM- WT 40000 KNM- ER 1470 • KNM-WT 40000 has a small cranial capacity but otherwise looks much like the famous KNM-ER 1470 fossil, generally referred to as Homo rudolfensis – These similarities are mostly in the face, and include the flat plane beneath the nose bone, the tall, vertically oriented cheek region, and the lack of a depression behind the ridge of the brow.

25. • The fossil resembles chimpanzees and A. anamensis in having a small earhole – It shares many other features of primitive hominins with A. afarensis and A. anamensis • Cheek teeth with thick enamel • A small brain the size of that of a chimpanzee • Flat nasal margins • It also has several important derived features – An anterior origin for the root of the cheekbone arch on the upper jaw – The existence of a flat plane beneath the nose bone (and so the appearance of a flat face) – A tall cheek region • Postcanine teeth and brow of the skull are smaller than in A. garhi Kenyapithecus platyops

26. Australopithecus africanus • A. africanus existed between 3 and 2 million years ago • Similar to afarensis, bipedal, but slightly larger body • Cranial capacity ranging between 420 and 500 cc • Molars are a little bigger than in afarensis Taung Child

27. Mrs. Ples (Sts 5) • The shape of the jaw is fully parabolic, like humans • The canine teeth, diastema in upper dentition, and sectorial first lower premolars are further reduced compared to A. afarensis

28. Australopithecus garhi

29. Australopithecus garhi • From Bouri, Middle Awash, Ethiopia, 2.5 m.y.a. • Large teeth – Cheek teeth at or beyond the robust australopithecine extremes – Large anterior teeth • Bigger than those of the largest australopithecines • Based on tooth size A. garhi fits with schemes that see gracile australopithecines as a direct human descendents – Canine-to-premolar/molar size ratios are comparable between A. garhi, the gracile australopithecines and early Homo • Long forelimbs and long hindlimbs • Researchers argue that A. garhi represents a direct ancestor of modern humans that is derived from africanus which is likely derived itself from afarensis

30. Australopithecus aethiopicus • Lived between 2.6 and 2.3 million years ago – Known from one major specimen, the Black Skull, and a lower jaw from Omo – May be an ancestor of robustus and boisei , but it has a baffling mixture of primitive and advanced traits • Brain size is small, at 410 cc

31. Australopithecus aethiopicus Australopithecus aethiopicus • Parts of the skull, particularly the hind portions, are very primitive, most resembling A. afarensis • The massive face, jaws, and single tooth found, and the largest sagittal crest (the bony ridge on top of the skull to which chewing muscles attach) in any known hominid, are more reminiscent of A. boisei

32. • Body similar to A. africanus , but larger and more robust skull, jaws, and teeth • Found primarily in cave deposits estimated at 1½ - 2 mya from Swartkrans and Kromdraai in South Africa • Massive face is flat or dished, with no forehead and large brow ridges • Relatively small front teeth, but massive grinding teeth (molars and premolars) in a large lower jaw • Most specimens have sagittal crests • Diet would have been mostly coarse, tough food that needed a lot of chewing • Average brain size is about 530 cc • Animala bones excavated with A. robustus skeletons suggest to some workers that the australopithecines may have used bones as digging tools Australopithecus robustus

33. Australopithecus boisei KNM-ER 406 Australopithecus boisei • A. boisei existed between 2.1 and 1.1 million years ago • Similar to A. robustus , but the face and cheek teeth even more massive • Cranial capacity averages about 530 cc • Some experts consider A. boisei and A. robustus to be variants of the same species – Others place them in a separate genus, Paranthropus

34. Gracile vs. Robust • Australopithecus afarensis and A. africanus are known as gracile australopithecines, because of their relatively lighter build, especially in the face and teeth – Gracile means slender, and in paleontology is used as an antonym to robust – Despite this, A. afarensis and A. africanus were still more dentally robust than modern humans • Australopithecus aethiopicus , A. robustus and A. boisei are known as robust australopithecines, because their skulls are more heavily built – The jaws, cheek teeth, and face are the most heavily built aspects of these fossil hominids – The canine teeth are quite small in all of these species

35. Homo habilis • Fossils named “handy man” because of the suggestion of evidence of tools found in contemporary deposits • Lived between about 2.4 and 1.5 million years ago • Similar to australopithecines in many ways • Face is primitive, but projects less than in A. africanus

36. Homo habilis, • Back teeth are smaller than those of the australopithecines, but still considerably larger than modern humans • Average cranial capacity, at 650 cc, is larger than in australopithecines – Brain size varies between 500 and 800 cc, overlapping the australopithecines at the low end and H. erectus at the high end • Brain shape is more humanlike – Bulge of Broca's area, essential for speech, is visible in one H. habilis brain cast, indicating it may have been capable of rudimentary speech • H. habilis was about 127 cm (5'0") tall, and about 45 kg (100 lb) in weight, although females may have been smaller • Habilis has been a controversial species – Some scientists have not accepted it, believing that all H. habilis specimens should be assigned to either the australopithecines or Homo erectus – Many now believe that Homo habilis combines specimens from two or three different species • Homo habilis • Homo rudolfensis • Homo ergaster

37. Homo rudolfensis • The species designation of Homo rudolfensis is much debated – Is it a separate species – Is it an australopithecine rather than a “homo” • One of the main problems with H. rudolfensis species is that there are no postcranial remains – Large brains in conjunction with megadont postcanines – Some researchers see the larger brain and tooth size as indicative of allometric changes due to increased body size-- rudolfensis and habilis are the same, with the former the males and the later the females – Some see rudolfensis as the ancestor of habilis with a decrease in brain size occurring – Others see the two on completely different evolutionary lines KNM-ER 1470 Homo rudolfensis

38. Homo ergaster • Homo ergaster is one of the more problematic of species designations • Each researcher that sees ergaster as valid sees different specimens as belonging or not belonging • Most researchers see too little difference between ergaster and erectus to form the basis of a species • As a general rule of thumb, one can consider most attributed ergaster specimens to be early erectus geographically confined to Africa KNM-WT 15000

39. Homo erectus from Zhoukoudian • Wolpoff claims that H. erectus is an invalid taxon, though few accept this interpretation at this point in time • Others believe the material attributed to erectus should be split into several different taxons – Asian and later African material remaining as H. erectus --not contributing to modern humans – Early African material as H. ergaster – European material as H. heidelbergensis

40. KNM-ER 3733 Homo erectus • An increase in brain size to approximately 900 cc • Reduction in postcanine dentition and a decrease in jaw size • Vertical shortening of the face. • Shortening arm bones, especially forearms to very modern limb proportions – Postcranial proportions are very similar to tropically adapted modern humans • Development of a more barrel-shaped chest • The formation of an external nose • Modern human size in terms of height

41. Homo antecessor • Approximate brain size of 1000 cc • Marked double-arched browridge – like later Neanderthals and Chinese H. erectus • Canine fossa but no expanded maxilla – May be due to the individual's young age since others (ATD 6- 58) have an expanded maxilla • Sharp nasal margin • Shallow maxillary notch • Reduced mandibular corpus thickness when compared to H. ergaster or early H. erectus • Small postcanines that resemble those of the habilines • M3 reduced relative to M1 • Moderate taurodontism – Characteristic of H. erectus and H. heidelbergensis ) • Large I2 dimensions that resemble H. heidelbergensis

42. Gran Dolina Material Homo antecessor

43. Homo antecessor • An important feature that was discovered when the remains were examined were cut marks that were present on most of the material – 12 parallel cut marks on a temporal fragment where the sternocleidomastoid muscle attaches – Cut marks on two foot phalanges where the flexor muscle lies • Dismemberment was the likely goal • Faunal material shows the same cut marks as the hominid remains – Very few carnivore tooth marks indicates that hominids were mainly responsible for processing the bones • This is the earliest well-documented case of cannibalism in a hominid population, and this information is important for deciphering the behavior of early hominids

44. Homo heidelbergensis from Arago

45. Homo heidlebergensis • An increase in brain size to approximately 1200cc • A shift in the widest part of the brain case from the cranial base to the parietal regions • The rear of the cranial vault becomes more vertical • A gradual reduction in cranial robusticity • A decline in postcranial robusticity • A tendency for a shift from shorter more robust stature to taller, leaner bodies

46. Neanderthal 1 La Chapelle-aux-Saints Homo neanderthalensis Mount Circeo Homo neanderthalensis • An occipital bun • A suprainiac fossa • Position of the mastoid crest located behind the external auditory meatus • Position of the juxtamastoid crest located behind the mastoid crest, and often larger than the mastoid process • Position of the mastoid process • The supraorbital torus • The supratoral sulcus • A receding frontal • Presence of lambdoidal flattening