West Turkana

The Simiolus excavation site at Moruorot South (S.C.)

The West Turkana Miocene Project is co-directed by James Rossie (Stony Brook University) and Susanne Cote (University of Calgary). The WTMP currently focuses on fieldwork at three sites within the Lothidok Formation of the Lothidok Range; one middle Miocene, and two early Miocene. Hominoids are found at all three sites, but monkeys have yet to be discovered.

Map of the Lothidok Formation (Boschetto, 1992)

Map showing the location of the Lothidok Formation in the Turkana Basin (Boschetto, 1992)

Rahab Kinyanjui and Bill Lukins collecting paleosol samples at Kalodirr (J.R.)

Kalodirr
A thick sequence of fossiliferous sediments is exposed at Kalodirr. The fossil apes Afropithecus, Turkanapithecus, and Simiolus are found at numerous localities throughout the section, alongside a diverse fauna. Fossil leaves are also found here, providing the opportunity to further reconstruct the paleoenvironment. Previous radiometric dating places the localities between 16.8 and 17.5 Ma, and our current work aims to refine the ages of localities within the site.

Moruorot
Moruorot is a smaller set of localities of the same age as those at Kalodirr, and likely deposited by the same system. Although it was discovered far earlier than Kalodirr (in 1933), less work has been done here. We have focused much of our work here in recent years because of the discovery of a paleosol that preserved partial skeletons, including those of a snake, a carnivore (including a complete skull), and the small ape Simiolus. The Simiolus skeleton is the most complete skeleton of a small-bodied hominoid found to date.

Partial skeleton of Simiolus from Moruorot South (J.R.)

Simiolus finger bones found in situ (J.R.)

Moruorot fossil exposures viewed from the slopes of Mt. Moruorot (S.C.)

Drainage gully below the Simiolus excavation at Moruorot South (S.C.)

Bovid horn core at Esha (J.R.)

Middle Miocene - Esha
Our study area also includes deposits dating to the middle Miocene. Middle Miocene localities were documented around Esha Hill in the 1980s (Boschetto et al., 1992), but little work has been done here. Primates from this site include a canine that resembles that of Kenyapithecus. If that genus is indeed present, it would be its latest occurrence, at younger than 13.2 Ma.

The geology crew crossing the beautiful Turkwell River to get to the sites (S.C.)

James (l) and Stephen Longoria (r) excavating at Moruorot (S.C.)

Relevant Publications
• Peppe, D., McNulty, K., MacLatchy, L. M., Rossie, J. B., et al. (2015) Research on East African Catarrhine and Hominoid Evolution (REACHE): a regional approach to understanding early Miocene paleobiology and paleoenvironments. Geological Society of America Abstracts with Programs. 47 (7): 286
• McNulty, K. P., MacLatchy, L., Rossie, J. B., et al. (2014) Research on East African catarrhine and hominoid evolution: Results from the first year. Am J Phys Anthrop Suppl. 153: 182
• Rossie, J. B., & MacLatchy, L. (2013) Dentognathic remains of an Afropithecus individual from Kalodirr, Kenya. J. Hum. Evol. 65: 199-208.
• Rossie, J. B., Gutierrez, M., Goble, E. (2012) Fossil forelimbs of Simiolus from Moruorot, Kenya. Am J Phys Anthrop Suppl. 54: 252
• Boschetto HB, Brown FH, and McDougall I (1992) Stratigraphy of the Lothidok Range, northern Kenya, and K/Ar ages of its Miocene primates. J. hum. Evol. 22:47-71.
• Leakey REF, and Leakey MG (1987) A new Miocene small-bodied ape from Kenya. J. hum. Evol. 16:369-387.
• Leakey REF, and Leakey MG (1986a) A new Miocene hominoid from Kenya. Nature 324:143-146.
• Leakey REF, and Leakey MG (1986b) A second new Miocene hominoid from Kenya. Nature 324:146-149
• Arambourg W (1933) Mammiféres Miocene du Turkana (Afrique Orientale). C. Ann. Paleont. 22:121-146