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Home , Afropithecus, Equatorius, Morotopithecus, Nacholapithecus, Nakalipithecus, Otavipithecus

Chapter Five: before the Bipeds hominoids • Objectives: – Understanding major radiation events during Miocene • Radiation of -like hominoids • Radiation of -like hominoids – Understanding the importance of Miocene hominoids in relation to • That African were more closely related to than either one was to • Evolutionary lineages leading to modern African apes and humans diverged sometime later than it has been thought – Understanding the importance of climate forcing/shift in relation to hominoids speciation • Primitive Early Miocene hominoids of E. differed markedly from Middle and Late Miocene hominoids of Africa and Eurasia – Dietary partitioning were important among Miocene hominoids: » Early Miocene hominoids  enamel with high dentine penetrance forming dentine pits () » Middle and Late Miocene hominoids  thickened molar enamel and other cranial features similar to Pongo (, , Ankarapithecus) » Middle Miocene hominoids from Eurasia  share some cranial and postcranial morphological features with later hominins (, Ouranopithecus) Miocene hominoids

• What are the issues regarding our understanding of the Miocene and hominin evolution?

• Are humans descended from ? Why or why not?

• Why is the Miocene period so important?

• Which is a missing link? Why is this notion false? The Earliest Primates

• The end of the Paleocene epoch marked a shift in climate patterns (global warming) that caused greater rainfall and higher temperatures.

• The increased size of tropical forests and warmer temperatures facilitated the spread and adaptive radiation of primates into new areas.

• Hominoidea is a Superfamily that is represented by four major families: • • Griphopithecidae • • Ponginae

Era Period Epoch Age The Last 65 Last The Million Years Ago Holocene 0.12

Pleistocene Quaternary 1.8

Pliocene

5.3 Neogene Miocene

Cenozoic 23.0

Oligocene 33.9

Eocene

Paleogene 55.8

Paleocene 65.5 archaic fossil catarrhines

• The Oligocene period (35 – 28 Ma) saw a radiation of anthropoids in Eurasia, Africa, Asia, and the Americas. • Fossil primates from this period are considered to be archaic catarrhines. • Oligocene and many Miocene fossil catarrhines are not necessarily related to the modern catarrhines • However, they tend to posses morphologies somewhat similar to modern catarrhines characteristics. Primate dental variation

• Dentine pits primates

• nakayamai

• Nakali, (9.9 – 9.8 Mya)

• It resembles Ouranopithecus macedoniensis (9.6 – 8.7 Ma, from Greece) Afro-Arabian Eurasia Land bridge (25 – 15 Mya)

Expansion and shrinking of the Tethys Sea had greater implications on climate Late Oligocene/Early Miocene

• Old World anthropoids including the families: – Propliopithecidae – Pliopithecidae – Cercopithecidae – Proconsulidae – Hylobatidae – Hominidae – Dendropithecus-group (Afro-Eurasian higher primates of the Miocene period) Oligocene-Miocene primates of Africa

• Archaic catarrhines (Propliopithecidae)

• Are not necessarily related to modern catarrhines

• Share some morphological similarities with modern catarrhines

Aegyptopithecus zeuxis from Fayum, Egypt The earliest dental apes

dental Apes with Y-5 molar pattern Distribution of fossil primates during the Middle Miocene General morphology

• Ancestors of living catarrhines (Cercopithecoidea and Hominoidea), characterized by: – a dental formula consisting of 2-1-2-3 – Single-cusped teeth – Bilateral compressed P3 – Honing of C1 – Five-cusped lower molars with no paraconid – M2 rather large than M1 but only slightly smaller than M3 – Moderately prominent glabella, separate from the supraorbital tori – A tubular external auditory meatus – A moderately developed mandibular inferior transverse torus – A long mandibular ramus with nearly vertical anterior margin – A U-shaped mandibular arcade – Very reduced olfactory lobes of the brain. Africa during the Miocene

• Major events – Formation of the East African Rift Valley System

• Formed during the Oligocene/Miocene period

• Tinderet and Kisingiri tuffs well known Early Miocene hominoids

• Kisingiri tuffs are about 17 – 18 Mya

• Tinderet tuffs are about 19 Mya East African Miocene Sites The Eastern African Rift Valley System Formation of Rift Valleys and Basins

- Rising hot molten rock causes up arching of the brittle continental crust creating a long linear depression (rift valley) bordered by bounding faults

- The process of tearing the crust apart (rifting) produces many smaller parallel faults and depressions, i.e. rift basins

- A 100 km cross section through a complex rift valley system reveals a jumble of tilted blocks, an exploding volcano, and lakes infilling the low areas (basins) Fault-bounded margin of a rift valley

Examples of an active volcano: - Ol Doinyo Lengai is 2980 meter high active volcano. - Eruptions of ash, steam and bombs are common and it has an unusual composition of sodium and potassium carbonates (sources for radiometric dating) River incision related to tectonic activities

Examples of uplifting: 1. Uplift and tilting are common in areas of rifting. 2. Movements of the Earth surface, called tectonism, causes rivers to change their course or down cut. 3. located adjacent to the rift is an example of river incision. 4. The Gorge was incised into the Serengeti Plain during Late time. The Earliest Apes: Dental Apes of the Miocene Period

• A period marked by radiation of apelike primate forms “the golden age of hominoids”. • Significant changes in climate and geography occurred during this period: the early Miocene was considerably warmer than the Oligocene. • Middle Miocene (~ 16 mya), Arabia formed a geographical connection (land-bridge) between Africa and Eurasia. • The Afro-Arabian land bridge made it possible for Miocene hominoids to spread from Africa throughout Eurasia. • The Miocene hominoid assemblage is large and complex, subsequently treated geographically. • The group is also know as a dental ape group; exhibiting a Y-5 molar pattern East African Miocene Sites

– East African Late Miocene faunas are poorly understood • Therefore any notable ecological changes associated with Late Miocene hominoids in East Africa is very patchy – Formation of the East African Rift Valley and its highlands had greater implication in climate patterns on the region • Early Miocene climate in East Africa was wetter than it is at present The Proconsulidae group • A group of Early Miocene hominoids found primarily in East Africa – They represent a major radiation of apelike primates (and probably some stem catarrhines) • The group consist of two subfamilies: – The Proconsulinae (three genera recognized) spanning from 23 – 15 Mya • Proconsul • • Turkanapithecus – The Afropithecinae (three genera recognized) dated between 18 – 15 Mya • • • Heliopithecus Miocene Primates: 23 - 5 mya • Early Miocene Proto-Apes – Proconsul • First described in 1933 from discovered at Koru – P. africanus, P. heseloni, P. nyanzae, P. major • Highly diversified group – Early Miocene sites of northern and Western Kenya » Rusinga and Mfwangano Islands in Lake Victoria, Songhor and Koru in northern Kenya • Habitat – Generally associated with forested environments – Linked specifically to hominoid primates Reconstruction of (Natural History Museum Gallery)

Known from Northern and Western Kenya

Oligocene/Miocene Proconsul africanus and Proconsul heseloni

• P. africanus and P. heseloni are the smallest in

• intermediate dental morphs between and (having gracile jaws and teeth with thin enamel)

• Body weight ranging from ~9 to 12 kgs • Morphologically light built

• P. heseloni lacks the supraorbital tori and strong muscular markings and facial prognathism

• Crania capacity of P. heseloni is estimated to be about 167 cc

• Postcranial morphology very mosaic – its intermembral index is 87% resembling that of most arboreal quadrupedal monkeys

• Postcranial skeleton of P. nyanzae is well known – It lacks the ischial callosities seen in Old World Monkeys and gibbons – Its sacrolumbar region indicate that it lacks a tail and the ischial tuberosity – Its intermebral index is estimated to be between 85 – 90% and a monkey-like features of the trunk • Pronograde posture, flexible vertebral column, and a narrow rib cage The Afropithecus turkanensis

• Afropithecus turkanensis (KNM-WK 16999) – Found by Richard and Meave Leakey in 1986 at Kalodirr, Kenya

– It is a large hominoid which possessed: • a relatively long snout • long and steep nasal bones • a wide interorbital distance • thin browridges • a sagittal crest with temporal lines which merge together on the frontal just above the browridge • procumbent with large and broad central incisors • large tusk-like canines • a shallow plate, deep and robust jaw and parallel tooth rows • thick enameled teeth Summary of African Early and Middle Miocene apelike radiation

• The East African Miocene families Proconsulidae and Afropithecidae represent a major radiation of apelike primates (earliest apes)

– Proconsulidae at least may represent stem catarrhines (the population that gave rise to the Old World monkeys and apes)

• The larger-bodied apes allocated to the Afropithecidae family include the genera Afropithecus, Morotopithecus, and Heliopithecus, which date from 18 – 15 Mya

• Members of the Proconsulidae group had been living in the forests of Africa long before their sister group the Afropithecidae

– Most likely the divergence of the two groups occurred when Africa was experiencing some climatic shift, when some groups left the forest and moved out into more open areas (mosaic environments).

– Afropithecidae increasingly occupied more open woodland and grasslands, thus developing a dietary preference for hard and tough food items requiring extensive food preparation before digestion takes place Middle Miocene hominoids • Geographic distribution: – Fossil remains of Middle Miocene hominoids have been found at numerous number of sites in Eurasia • Spain, France, Germany, Austria, Greece, Hungary, Georgia, Turkey, India, Nepal, and China – In Africa, they have been found at a few sites mostly in: • Kenya – at Fort Ternan, Tugen Hills, and Maboko Island • Namibia – at Otavi Mountains – During the early phase of the Middle Miocene, roughly between 13 and 15 Ma, several new hominoid appeared in Africa, such as , Kenyapithecus and

• Dryopithecus and Sivapithecus cross the Middle/Late Miocene boundary

• Dryopithecus, is perhaps one of the most interesting Middle/Late Miocene hominoids that was widely distributed. Middle-Later Miocene climates and the radiation of Eurasian hominoids • At the transition between Middle and Late Miocene there was an expansion of continental ice sheets and increased ice buildup in the Antarctica – The breakup of Australia from Antarctica significantly changed the ocean currents and their circulation resulting in dramatic worldwide Middle/Late Miocene Apes

– Dryopithecus fontani • First discovered near the village of Saint Gaudens, France in 1856 • Many more specimens have been discovered throughout Europe • Dentally it shows large canines with a honing facet on the lower and similar wear on the molars • It has thin enamel, a 2:1:2:3 dental formula, low rounded cusps adapted for fruit eating • It has small incisors (contrasting the extant ape incisors size) • It has a more ape-like postcranial skeleton, such as a reduced olecranon process and a deep humeral trochlea. Dryopithecus fontani Reconstruction of Dryopithecus fontani (Natural History Museum Gallery) Sivapithecus sivalensis • This species was formerly known as Sivapithecus indicus and as Ramapithecus punjabicus and as Dryopithecus punjabicus • First remains discovered by David Pilbeam and his team in 1979-1980 at Siwalik in the Potwar Plateau of Pakistan. • The remains (GSP 1500) consists of the left side of the face with a nearly complete mandible (with complete ) • Overall, facial structure includes a combination of delicate, thin bone coupled with large jaws and teeth • Facial morphology is orangutan-like in a number of features: – Dished facial profile with upraised alveoli – Subnasal morphology, oblong orbits, and narrow interorbital distance – Lack of browridge development, and large sized central incisors – Dental formula of 2:1:2:3, thick enameled teeth with loss of cingulum around the base of the molars • Postcranially, Sivapithecus was arboreal quadruped-climber with no evidence for brachiating – It possessed a mobile hip joint, a grasping big toe, curved toe bones, and a modern apelike elbow and a shoulder with traits similar to that of Proconsul (incapable of prolonged arm-swinging) • Systematically, Sivapithecus remains unclear – Sivapithecus Indicus, existing 12.5 - 10.5 mya – Sivapithecus Sivalensis, existing 9.5 - 8.5 mya – Sivapithecus Parvada, existing around 10 mya Sivapithecus sivalensis Reconstruction of Sivapithecus indicus Morotopithecus bishopi

• Discovered by Daniel Gebo and his co-workers in Moroto, Uganda. • This find is dated to 20.6 Mya •It exhibits primitive features of the upper jaw and derived features of the shoulder joint indicating suspensory behaviors Otavipithecus namibiensis

• Miocene hominoid (first and most complete fossil ape) from Namibia (Sub-equatorial Africa) • represents a significant addition to the taxonomically sparse African middle Miocene hominoid fossil record. • The Otavipithecus comprises a mandible, which presents a unique mosaic of dental and gnathic characters • The mandible has unique characteristics that differentiate it from other middle Miocene hominoids of Africa and Eurasia – it represents the only fossil evidence documenting a pre- stage of hominoid evolution in southern Africa • several attributed cranial and postcranial elements resembling the stem hominoid Proconsul • Otavipithecus is most closely related to Afropithecus Otavipithecus namibiensis mandible, femoral fragment (proximal femur), and manual phalanges Nacholapithecus kerioi crania and postcranial remains africanus Recent discovery of Middle Miocene hominoid from Tugen Hills, Kenya • Equatorius africanus: – Is a partial hominoid skeleton (about 15 million years) from Tugen Hills of north central Kenya – It mandates a revision of the hominoid genus Kenyapithecus, a possible early member of the great ape-human clade • Equatorius africanus also manifests an array of derived features (collectively distinguishing it from the Early Miocene genera): – Reduced premolar and molar cingulae • Derived postcranial morphology include: – a robust and relatively straight clavicle – reduced and posteriorly deflected humeral medial epicondyle – reduced radial fossa relative to the coronoid fossa on the distal humerus – ulna with heavily buttressed coronoid process and strongly developed supinator crest Molecular Clock and hominoid classification • DNA evidence for branching pattern of hominoids, which assumes a constant rate of mutation through time, can be calibrated in time with reference to known fossils. • For example, dates for fossil Sivapithecus (Middle/late Miocene ape) and Proconsul (ancestral to all living hominoids) imply that between 4 – 6 Mya, a separation of hominids from the ancestral apes (and common ancestor with chimpanzees) occurred. • Fossil primates from this particular window in our evolutionary tree are very important, however, there almost no fossil hominoids from this period (with the exception of Orrorin and )