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104 ASM Lecture #11 The Genus Paranthropus ( Robust Australopithecines ) Hominid Synapomorphies 3 FUNCTIONAL COMPLEXES: Neurological Changes: Expansion in brain size Less projecting face tucked under braincase more Reduced Anterior Teeth Chewing Complex: Small canines No canine-premolar honing complex (i.e., no sectorial premolar) Bipedal Locomotion 1 ASM 104 Lecture #11 Early Hominid Sites Localities of Early Gracile Australopithecines Ardipithecus ramidus Australopithecus anamensis A. afarensis A. bahrelghazali A. africanus Hominids Evolve 1. Many phylogenetic relationships have been proposed for the the australopithecines. 2. There is significant overlap among these species in the fossil record. More than one species exists at one time. 3. Sometime between 2 and 3 mya, a fossil hominid evolved that kept a small brain and small body, but developed a huge masticatory system = Paranthropus. 4. About 2.5 mya, another hominid genus appears, Homo. 2 ASM 104 Lecture #11 What Happened from 3.0 - 2.5 mya? Global climatic change hypothesized to have caused panAfrican habitat change between 2.8 2.5 mya Diversification of hominids into Paranthropus and Homo (cladogenesis) 3.5 mya 2.0 mya Cladogenesis Splitting of one species into 2+ new species Remember: there is controversy over this model. Some very influential scientists think Kenyanthropus led to Homo and Australopithecus to Paranthropus. B cies Spe Specie sA o Hom Ancestral Species Australopithecus P ar a nthr opu s Think about what this view does to the popular view of Lucy . Robust Lineage = Paranthropus Thought to have focused on hard food items Existed in eastern and southern Africa Co-existed with Homo species Digging sticks, but no stone tools 3 ASM 104 Lecture #11 Homo Lineage Incorporated meat into diet Co-existed with Paranthropus species Stone tools Migrated out of Africa .1 .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Australopithecus anamensis Homo Paranthropus Paranthropus robustus Paranthropus boisei Australopithecus garhi Paranthropus aethiopicus Kenyanthropus platyops Australopithecus africanus Australopithecus afarensis 4.5 Ardipithecus ramidus 5.5 6.0 Orrorin tugenensis Sahelanthropus tchadensis Robust Australopithecines = Paranthropus Dietary morphology in comparison to gracile hominids Increased enamel thickness Increased mandibular robusticity Smaller incisors and canines in straight row Megadont cheek teeth Sagittal crests 4 ASM 104 Lecture #11 Australopithecus garhi Possible Paranthropus ancestor Megadont cheek teeth Localities Bouri, Ethiopia Dates ~2.5 mya Robust Localities x xx x x x X= P. aethiopicus X= P. boisei X= P. robustus x x xx Paranthropus aethiopicus Name par = parallels anthropos = human aethiopicus = Ethiopia Parallels humans, from Ethiopia Localities West Turkana, Kenya Omo, Ethiopia Dates ~2.5 mya 5 ASM 104 Lecture #11 Paranthropus aethiopicus Most primitive species of robust lineage Retains relatively long snout Cranial base similar to A. afarensis Small brain Marked postorbital constriction Paranthropus aethiopicus Megadont cheek teeth Wide, flaring zygomatics Huge sagittal and nuchal crests Large temporal foramen Dished face A. afarensis vs. P. aethiopicus 6 ASM 104 Lecture #11 A. africanus vs. P. aethiopicus Paranthropus Name robustus robustus = robust Localities: South Africa Swartkrans Kromdraai Drimolen Gladysvale Gondolin Dates ~2.2 - 1.2 mya P. robustus Characteristics Thick mandible Dished face Tall, flaring zygomatic arches Large temporal foramen Thick palate Larger cranial capacity than P. aethiopicus Less prognathic than P. aethiopicus More robust than P. aethiopicus 7 ASM 104 Lecture #11 Paranthropus robustus Dental Characteristics Small incisors and canines in straight row Huge cheek teeth Thick enamel Teeth worn flat and appear used more in crushing Paranthropus boisei Name boisei = named after Boise (person) Localities Konso, Ethiopia Omo, Ethiopia West Turkana, Kenya Koobi Fora, Kenya Olduvai, Tanzania Dates ~2.2 - 1.2 mya Paranthropus boisei Characteristics Tends to be larger than P. robustus and hyper robust Gaping temporal fossa Deep palate Huge cheek teeth and small anterior dentition Dished face Evidence for sexual dimorphism 8 ASM 104 Lecture #11 Masticatory Muscles temporalis masseter Sagittal Crest Male Gorilla Molarization of the Premolar Premolar A. afarensis P. boisei 9 ASM 104 Lecture #11 Overall Ecology of the Robust Lineage Paleoecology Edaphic grasslands and associated wetlands, and rivers Powerful chewing muscles indicate adaptation for hard food items Paranthropus = highly specialized to its environment and food source Possible Food Items of the Robust Lineage Harder and/or tougher foods than gracile lineage Probably nuts, hard seed, fibrous tubers Possibly some meat and termites ? Or Was It? New research (Ungar, 2008) on Paranthropus teeth (microscopic examination of wear and damage): NOT the pattern expected for a regular diet of hard foods ? So what does this mean? Anatomy suggests what [Paranthropus] could eat, but not necessarily what it did eat. Think back to natural selection Why would an entire genus of hominids be super adapted to eating a kind of food it didn t have to eat all the time? 10 ASM 104 Lecture #11 Paranthropus Tools In South Africa Bone digging sticks have been recovered from Swartkrans Microscopic examination of the wear patterns on these tools show them to have been likely used for digging into termite mounds Paranthropus Ecology Prey - not predators P. robustus cranium with leopard (or another predator) tooth marks Differences between Gracile & Robust Australopithecines Gracile small temporal fossa more prognathic face under neurocranium less robust zygomatic maxillary/incisor prognathism larger incisors and canines smaller premolars and molars Robust large temporal fossa less prognathic face high on neurocranium more robust zygomatic flatter or dished face smaller incisors and canines megadont premolars and molars 11 ASM 104 Lecture #11 Overall Differences between Gracile and Robust Australopithecus Paranthropus Phylogeny: Paranthropus = Evolutionary Dead End Extinction of Paranthropus Persisted for ~1.3 million years (2.5 - 1.2 mya) Another climate change around 1.2 mya It may have been too specialized to adapt Paranthropus disappears from the fossil record Extinct A. garhi 12 ASM 104 Lecture #11 Kenyanthropus platyops ? 13

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