The Abrahamskraal Formation is a geological formation and is found in numerous localities in the Northern Cape, Western Cape, and the Eastern Cape of South Africa. It is the lowermost formation of the Adelaide Subgroup of the Beaufort Group, a major geological group that forms part of the greater Karoo Supergroup. It represents the first fully terrestrial geological deposits of the Karoo Basin. Outcrops of the Abrahamskraal Formation are found from the small town Middelpos in its westernmost localities, then around Sutherland, the Moordenaarskaroo north of Laingsburg, Williston, Fraserburg, Leeu-Gamka, Loxton, and Victoria West in the Western Cape and Northern Cape. In the Eastern Cape outcrops are known from Rietbron, north of Klipplaat and Grahamstown, and also southwest of East London.

Geology The Abrahamskraal Formation comprises the majority of the Middle Permian Beaufort sequence, and are thought to range between 268 - 259 million years in age. The lowermost deposits of the Abrahamskraal Formation found in the Eastern Cape until recently were named the Koonap Formation, but these outcrops have been amalgamated into the Abrahamskraal Formation due to recent stratigraphic and biostratigraphic research. The Abrahamskraal Formation incorporates the entire Tapinocephalus Assemblage Zone in its upper sections and the entire Eodicynodon Assemblage Zone its lowermost southern deposits. In the west and northerly deposits the Abrahamskraal Formation overlies the Waterford Formation and the Middleton Formation in the south, both formations containing the uppermost deposits of the Ecca Group. The lower boundary of the Tapinocephalus Assembalge Zone is dated to 264.4 million years ago,while the boundary between Eosimops-Glanosuchus and Diictodon-Styracocephalus subzones is dated to 262 million years ago. The Karelskraal Member is dated to 261 to 260 million years ago and is timed to the onset of the Capitanian mass extinction event.

The rocks of the Abrahamskraal Formation comprise mainly greenish-grey to blueish-grey mudstone coupled with rarer instances of greyish-red, reddish-brown or purple mudstones. These include subordinate greenish-grey, fine-grained sandstones which are normally observed in fining upward cycles. The sandstones vary in thickness from several metres to several tens of metres in some localities. Siltstones are also found interbedded with the mudstone beds. The presence of these rocks reveal much about the past environment that they were deposited in. They were formed by sedimentary material being deposited in the Karoo Basin - a retro-arc foreland basin - by vast, low-energy alluvial plains flowing northwards from the south. The lowermost deposits are considered to be deltaic and grade laterally into the underlying Ecca Group deposits in its southern localities. Deposits grade steadily younger in the northeast where the sedimentary facies turn fully terrestrial. The greenish-grey mudstones are usually associated with the deltaic sedimentary facies while the redder mudstones with the terrestrial.Rubidge, B. S. (ed.) 1995b. Biostratigraphy of the Beaufort Group (Karoo Supergroup). South African Committee of Stratigraphy. Biostratigraphic Series 1. Pretoria, Council for Geoscience.

All sedimentary rocks of the Karoo Basin were transported downhill from the south in the shadow of the rising Gondwanide mountain range. The Gondwanides were the result of tectonic uplift that had previously begun to take course due to subduction of the Palaeo-pacific plate beneath the Gondwanan Plate. Orogenic pulses from the growing Gondwanides mountain chain and associated subduction created accommodation space for sedimentation in the Karoo Basin where the deposits of the Abrahamskraal Formation and all succeeding deposits of the Karoo Basin were deposited over millions of years.Kitching, J. W. (1970). A short review of the Beaufort zoning in South Africa. In Second Gondwana Symposium Proceedings and Papers (Vol. 1, pp. 309-312).Keyser, A.W. and Smith, R.M.H., 1978. Vertebrate biozonation of the Beaufort Group with special reference to the western Karoo Basin. Geological Survey, Department of Mineral And Energy Affairs, Republic of South Africa.

Paleontological significance The Abrahamskraal Formation is highly fossiliferous and well known for its biozone assemblages of therapsid fossils. The Eodicynodon and Tapinocephalus Assemblage Zones to which this geological formation incorporates preserve the first appearance of the earliest dicynodonts, dinocephalians, biarmosuchians, therocephalians, gorgonopsians, and pareiasaurian parareptiles.Cluver, M.A., 1975. A New Didynodont Reptile from the Tapinocephalus Zone [Karoo System, Beaufort Series] of South Africa, with Evidence of the Jaw Adductor Musculature.Boonstra, L. D. 1948. Anomodont reptiles from the Tapinocephalus zone of the Karroo System. In: Du Toit, A. L. (ed.) Special Publications of the Royal Society of South Africa. Robert Broom Commemorative Volume., 57-64. Cape Town: The Royal Society. The upper sections of this formation document the rise of and diversification of the dinocephalians.Boonstra, L.D., 1969. The fauna of the Tapinocephalus Zone (Beaufort beds of the Karoo)Atayman, S., Rubidge, B.S. and Abdala, F., 2009. Taxonomic re-evaluation of tapinocephalid dinocephalians. Palaeontologia africana, 44, p.88Á90. Link: https://core.ac.uk/download/pdf/39675877.pdf#page=88 The dinocephalians subsequently went extinct at the contact of the Abrahamskraal Formation with the overlying Teekloof Formation.Lucas, S.G., 2001. A global hiatus in the Middle Permian tetrapod fossil record. Permophiles, 38, pp.24-27. Link: http://www.nigpas.ac.cn/qt/tethys_en/edit/UploadFile/200568142141602.pdf#page=26 The basal pelycosaur synapsid species, Elliotsmithia longiceps, has also been found in the deposits of this formation. The presence of this basal synapsid is indicative of this geological formations significance. For decades, paleontologists have puzzled over what has been termed Olsen's Gap, which is used to describe the evolutionary gap in the tetrapod fossil record between the appearance of the more derived therapsids and their ancestors, the pelycosaurs. The rocks of the Abrahamskraal Formation and its geological correlates abroad hold the promise of that fossil gap being bridged through future research endeavors in the years to come. More notable fossil species include the dicynodont Diictodon feliceps which first appears in the upper sections of this formation, remaining ubiquitous until the Permian-Triassic boundary.Cluver, M.A. and Hotton, N., 1981. The genera Dicynodon and Diictodon and their bearing on the classification of the Dicynodontia (Reptilia, Therapsida). South African Museum. Finally, fossils of temnospondyl amphibians such as of Rhinesuchus, the fish Namaichthys, invertebrate fossils of molluscs, invertebrate trackways and burrows, vertebrate footprints of therapsids, and a variety of plant fossils such as Dadoxylon, Equisetum modderdriftensis, Schizoneura africana, and several different species of Glossopteris have been recovered.

Among the species found in the Abrahamskraal Formation is Moschops Capensis

Paleobiota

Amphibians Amphibians of the Abrahamskraal Formation Taxa Species Locality Assemblage Zone Material Notes ImagesRhinesuchusMarsicano, Claudia & Latimer, Elizabeth & Rubidge, Bruce & Smith, Roger. (2017). The Rhinesuchidae and early history of the Stereospondyli (Amphibia: Temnospondyli) at the end of the Palaeozoic. Zoological Journal of the Linnean Society. 181. 10.1093/zoolinnean/zlw032. R. tenuceps Farm Stinkfontein, Prince Albert District Tapinocephalus A-Z. A skull associated with a partial left mandibular ramus. A temnospondyl amphibian. R. whaitsi Leeu-Gamka, Prince Albert District A basicranium, seven fragments of the middle portion of the left hemi-mandible, and multiple skull fragments.

Fish Actinopterygian Actinopterygians of the Abrahamskraal Formation Taxa Species Locality Assemblage Zone Material Notes ImagesBethesdaichthysB. kitchingi Blourug farm, Victoria West. Tapinocephalus A-Z A preserved skull. An actinopterygian fish.BlourugiaBender, P.A. (2005). A new deep-bodied Late Permian actinopterygian fish from the Beaufort Group, South Africa.B. seeleyi Blourug farm, Victoria West. Tapinocephalus A-Z A partial skeleton. An actinopterygian fish.WestlepisW. kempeni Blourug farm, Victoria West Tapinocephalus A-Z An actinopterygian fish.

Reptiles Sauropsida Sauropsids of the Abrahamskraal Formation Taxa Species Locality Assemblage Zone Material Notes ImagesAustralothyris A. smithi Beukesplaas farm Upper part of Tapinocephalus A-Z A skull and portions of the rest of the skeleton A procolophonomorph parareptile.Bradysaurus B. baini Prince Albert, Leeu Gamka, Hottentotsrivier Farm, Leeurivier, Mynhardtskraal, Groot Kruidfortein, Zwarts Siding, Sutherland, and Knoffelfortein. Tapinocephalus A-Z A complete skull and separate lower jaw with a complete postcranial skeleton consisting of a complete shoulder girdle and pelvis, a complete vertebral column with few missing at the end of the caudal vertebrae. The right fore and hind limbs are complete. The left humerus, radius, ulna, femur, tibia, and fibula are partially preserved.A pareiasaur. B. seeleyi A partial skeleton consists of a complete skull, lower jaw, partial vertebral column, some ribs, osteoderms, and parts of girdles.EmbrithosaurusE. schwarzi Hoogeveld farm. Tapinocephalus A-Z Distorted skull with the occluded lower jaw, vertebrae 1 to 27 with articulated osteoderms, two small articulated caudal vertebrae, partial left scapulocoracoid, cleithrum, left and right clavicle, and interclavicle, complete right humerus, partial left humerus, complete right radius, partial left radius, both ulnae complete, both femora complete, both tibia complete, right fibula, partial left fibula, complete pelvis, two digits of the forelimb and two digits of the hindlimb A pareiasaur.EunotosaurusE. africanus De bad farm, Prince Albert, Boesmanrivier and Rietfortien Upper Tapinocephalus A-Z and parts of Pristerognathus A-Z. Fossilized ribbones. An early relative of reptile.

Synapsids Therapsids Anomodonts Chainosauria Chainosaurs of the Abrahamskraal Formation Taxa Species Locality Assemblage Zone Material Notes ImagesGalechirus G. scholtzl Victoria West Tapinocephalus A-Z. A partial skeleton An insectivorous anomodont.PatranomodonP. nyaphulii Prince Albert Eodicynodon A-Z A fossilized skull A rare genus of anomodont.

Dicynodontia