# Abrahamskraal Formation

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 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.
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.

## 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. The upper sections of this formation document the rise of and diversification of the dinocephalians. The dinocephalians subsequently went extinct at the contact of the Abrahamskraal Formation with the overlying Teekloof Formation. 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. 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

| Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon | Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited. |

### Amphibians

Amphibians of the Abrahamskraal Formation :
| Taxa | Species | Locality | Assemblage Zone | Material | Notes | Images |
| Rhinesuchus | R. tenuceps | Farm Stinkfontein, Prince Albert District | Tapinocephalus A-Z. | A skull associated with a partial left mandibular ramus. | A temnospondyl amphibian. | |
| Rhinesuchus | R. whaitsi | Leeu-Gamka, Prince Albert District | Tapinocephalus A-Z. | A basicranium, seven fragments of the middle portion of the left hemi-mandible, and multiple skull fragments. | A temnospondyl amphibian. | |

### Fish
#### Actinopterygian

Actinopterygians of the Abrahamskraal Formation :
| Taxa | Species | Locality | Assemblage Zone | Material | Notes |
| Bethesdaichthys | B. kitchingi | Blourug farm, Victoria West. | Tapinocephalus A-Z | A preserved skull. | An actinopterygian fish. |
| Blourugia | B. seeleyi | Blourug farm, Victoria West. | Tapinocephalus A-Z | A partial skeleton. | An actinopterygian fish. |
| Westlepis | W. 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 |
| Australothyris | A. smithi | Beukesplaas farm | Upper part of Tapinocephalus A-Z | A skull and portions of the rest of the skeleton | A 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. |
| Bradysaurus | B. seeleyi | Prince Albert, Leeu Gamka, Hottentotsrivier Farm, Leeurivier, Mynhardtskraal, Groot Kruidfortein, Zwarts Siding, Sutherland, and Knoffelfortein. | Tapinocephalus A-Z | A partial skeleton consists of a complete skull, lower jaw, partial vertebral column, some ribs, osteoderms, and parts of girdles. | A pareiasaur. |
| Embrithosaurus | E. 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. |
| Eunotosaurus | E. 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 | Images |
| Galechirus | G. scholtzl | Victoria West | Tapinocephalus A-Z. | A partial skeleton | An insectivorous anomodont. | |
| Patranomodon | P. nyaphulii | Prince Albert | Eodicynodon A-Z | A fossilized skull | A rare genus of anomodont. | |

###### Dicynodontia

Dicynodonts of the Abrahamskraal Formation :
| Taxa | Species | Locality | Assemblage Zone | Material | Notes | Images |
| Brachyprosopus | B. broomi | Beukesplaas | Tapinocephalus A-Z | A skull. | A dicynodont. | Brachyprosopus broomiDiictodon Feliceps Emydops Arctatus Eodicynodon oosthuizeni Eosimops newtoniNyaphulia oelofseni Robertia broomiana |
| Colobodectes | C. cluveri | Keerom farm, Kruidfontein farm, Bastardsfontein farm, and Altringham farm. | Eodicynodon and Tapinocephalus A-Z | A skull lacking zygomatic arches and postorbital bars | A dicynodont. | Brachyprosopus broomiDiictodon Feliceps Emydops Arctatus Eodicynodon oosthuizeni Eosimops newtoniNyaphulia oelofseni Robertia broomiana |
| Diictodon | D. feliceps | Prince Albert. | Tapinocephalus A-Z | Several skeletal specimens. | A pylaecephalid dicynodont. | Brachyprosopus broomiDiictodon Feliceps Emydops Arctatus Eodicynodon oosthuizeni Eosimops newtoniNyaphulia oelofseni Robertia broomiana |
| Emydops | E. arctatus | Beaufort West and Prince Albert. | Either Tapinocephalus A-Z or Pristerognathus A-Z. | A partial skull | A dicynodont. | Brachyprosopus broomiDiictodon Feliceps Emydops Arctatus Eodicynodon oosthuizeni Eosimops newtoniNyaphulia oelofseni Robertia broomiana |
| Eodicynodon | E. oosthuizeni | Tuinkraal and Zwartskraal farm, Prince Albert district | Tapinocephalus A-Z | Postcranial skeleton. | A dicynodont. | Brachyprosopus broomiDiictodon Feliceps Emydops Arctatus Eodicynodon oosthuizeni Eosimops newtoniNyaphulia oelofseni Robertia broomiana |
| Eosimops | E. newtoni | Victoria West. | Tapinocephalus A-Z. | several skull specimens and one complete skeleton. | A pylaecephalid dicynodont. | Brachyprosopus broomiDiictodon Feliceps Emydops Arctatus Eodicynodon oosthuizeni Eosimops newtoniNyaphulia oelofseni Robertia broomiana |
| Nyaphulia | N. oelofseni | Botterkraal farm | Eodicynodon A-Z. | Partial skull, jaws, and teeth. | A dicynodont, formally named E. oelofseni. | Brachyprosopus broomiDiictodon Feliceps Emydops Arctatus Eodicynodon oosthuizeni Eosimops newtoniNyaphulia oelofseni Robertia broomiana |
| Robertia | R. broomiana | Klein Koedoeskop, Beaufort West. | Lower part of the Tapinocephalus A-Z. | Partial skull and postcranial skeleton. | A small herbivorous dicynodont. | Brachyprosopus broomiDiictodon Feliceps Emydops Arctatus Eodicynodon oosthuizeni Eosimops newtoniNyaphulia oelofseni Robertia broomiana |

##### Biarmosuchia

Biarmosuchians of the Abrahamskraal Formation :
| Taxa | Species | Locality | Assemblage Zone | Material | Notes |
| Hipposaurus | H. boonstrai | Beaufort west and Riet Fontein | Tapinocephalus A-Z | A single skull. | A hipposaurid therapsid. |
| Hipposaurus | H. brinki | Beaufort west and Riet Fontein | Tapinocephalus A-Z | A preserved skull. | A hipposaurid therapsid. |
| Impumlophantsi | I. boonstrai | Palmietfontein portion (plot 57) of Kruidfontein farm, Prince Albert District | Tapinocephalus A-Z | The preorbital region of the skull and articulated lower jaw and a partial vertebral column and pelvis | A Biarmosuchian. |
| Nierkoppia | N. brucei | Farm Stellenboschvlei | Tapinocephalus A-Z. | A relatively well-preserved fragment of skull roof, preserving the interorbital and inter-temporal regions and dorso-medial portion of the occiput. | A proburnetiine burnetiamorph. |

##### Dinocephalian
###### Anteosauridae

Anteosaurs of the Abrahamskraal Formation :
| Taxa | Species | Locality | Assemblage Zone | Material | Notes | Images |
| Anteosaurus | A. magnificus | Beaufort West, Prince Albert, and Laingsburg | Tapinocephalus A-Z. | Several complete skulls, dentition, and partial postcranial skeleton. | A large carnivorous anteosaur. | |
| Australosyodon | A. nyaphuli | Prince Albert and Tuinkraal | Eodicynodon A-Z. | A skull and mandible with a preserved left side. | A dinocephalian. | |

###### Styracocephalidae

Styracocephalids of the Abrahamskraal Formation :
| Taxa | Species | Locality | Assemblage Zone | Material | Notes | Images |
| Styracocephalus | S. platyrhynchus | Rietfontein, Prince Albert, and Boesmansrivier | Tapinocephalus A-Z. | Complete skull consists of jaws, palate, and dentition. | A dinocephalian therapsid. | |

###### Tapinocephalidae

Tapinocephalians of the Abrahamskraal Formation :
| Taxa | Species | Locality | Assemblage Zone | Material | Notes |
| Criocephalosaurus | C. vanderbyli | Prince Albert | Lower and Middle Tapinocephalus A-Z. | A skull cap consists of the frontals, parietals, postfrontals, and one pre-frontal. | A tapinocephalian. |
| Keratocephalus | K. moloch | Prince Albert, Leeu Gamka, and Buffelsvlei. | Tapinocephalus A-Z. | Variable skulls and postcrania. | A tapinocephalian. |
| Mormosaurus | M. seeleyi | Gouph tract | Tapinocephalus A-Z. | A partial skull. | A Tapinocephalian. |
| Moschops | M. capensis | De Cypher Farm and Hottentotsrivier. | Tapinocephalus A-Z. | Several skeletal specimens consist of skulls and postcranial skeletons. | A subaquatic tapinocephalian. |
| Moschops | M. koupensis | De Cypher Farm and Hottentotsrivier. | Tapinocephalus A-Z. | Several skeletal specimens consist of skulls and postcranial skeletons. | A subaquatic tapinocephalian. |
| Moschops | M. romeri | De Cypher Farm and Hottentotsrivier. | Tapinocephalus A-Z. | Several skeletal specimens consist of skulls and postcranial skeletons. | A subaquatic tapinocephalian. |
| Phocosaurus | P. megischion | Boesmansrivier and Vers Fontein/Jan Willem Fontein. | Tapinocephalus A-Z. | A partial skull. | A Tapinocephalian. |
| Tapinocaninus | T. pamelae | Modderdrift farm | Eodicynodon A-Z. | Paratypes consist of several skulls with few post-cranial skeletons. | A Tapinocephalian. |
| Tapinocephalus | T. atherstonei | Boesmanshoek and Prince Albert | Lower, Middle, and Upper part of the Tapinocephalus A-Z. | A skull and postcranial elements. | A giant herbivorous Tapinocephalian. |
| Struthiocephalus | S. whaitsi | Prince Albert | Lower to Middle Tapinocephalus A-Z. | A partial skull. | A Tapinocephalian. |

###### Titanosuchidae

Titanosuchids of the Abrahamskraal Formation :
| Taxa | Species | Locality | Assemblage Zone | Material | Notes |
| Jonkeria | J. boonstai | Farm Uitkyk, Leeu-Gamka, Groot kruidfontein, Prince Albert, and Vers Fontein. | Tapinocephalus A-Z. | A skull and humerus. | An omnivorous titanosuchid dinocephalian. |
| Jonkeria | J. ingens | Farm Uitkyk, Leeu-Gamka, Groot kruidfontein, Prince Albert, and Vers Fontein. | Tapinocephalus A-Z. | A complete skull. | An omnivorous titanosuchid dinocephalian. |
| Jonkeria | J. haughtoni | Farm Uitkyk, Leeu-Gamka, Groot kruidfontein, Prince Albert, and Vers Fontein. | Tapinocephalus A-Z. | A crushed skull. | An omnivorous titanosuchid dinocephalian. |
| Jonkeria | J. koupensis | Farm Uitkyk, Leeu-Gamka, Groot kruidfontein, Prince Albert, and Vers Fontein. | Tapinocephalus A-Z. | A complete pelvis bone. | An omnivorous titanosuchid dinocephalian. |
| Jonkeria | J. parva | Farm Uitkyk, Leeu-Gamka, Groot kruidfontein, Prince Albert, and Vers Fontein. | Tapinocephalus A-Z. | A femur, radius, small humerus, and tarsal. | An omnivorous titanosuchid dinocephalian. |
| Jonkeria | J. rossouwi | Farm Uitkyk, Leeu-Gamka, Groot kruidfontein, Prince Albert, and Vers Fontein. | Tapinocephalus A-Z. | The holotype consists of postcranial skeletons. | An omnivorous titanosuchid dinocephalian. |
| Jonkeria | J. truculenta | Farm Uitkyk, Leeu-Gamka, Groot kruidfontein, Prince Albert, and Vers Fontein. | Tapinocephalus A-Z. | A skull and partial skeleton. | An omnivorous titanosuchid dinocephalian. |
| Jonkeria | J. vanderbyli | Farm Uitkyk, Leeu-Gamka, Groot kruidfontein, Prince Albert, and Vers Fontein. | Tapinocephalus A-Z. | A complete skull. | An omnivorous titanosuchid dinocephalian. |
| Titanosuchus | T. ferox | Beaufort West, Prince Albert, Mynhardskraal, Veldmansrivier, and Lammerskraal. | Tapinocephalus A-Z | Fragmentary jaws and post-crania that include two left humeri, femur, and two phalanges. | A carnivorous titanosuchid dinocephalian. |

##### Gorgonopsia

Gorgonopsians of the Abrahamskraal Formation :
| Taxa | Species | Locality | Assemblage Zone | Material | Notes | Images |
| Aelurosaurus | A. felinus | Beaufort west. | Tapinocephalus A-Z. | A holotype preserved skull. | A gorgonopsian. | AelurosaurusEriphostoma |
| Aelurosaurus | A. whaitsi | Beaufort west. | Tapinocephalus A-Z. | A holotype preserved skull. | A gorgonopsian. | AelurosaurusEriphostoma |
| Cerdodon | C. tenuidens | Beaufort west. | Tapinocephalus A-Z. | A holotype consists of a crushed skull. | A gorgonopsid. | AelurosaurusEriphostoma |
| Eriphostoma | E. microdon | Prince Albert, Hottentotsrivier farm, and Mynhardtskraal. | Tapinocephalus A-Z. | Partial skull remains. | A gorgonopsid formally named Galesuchus gracilis. | AelurosaurusEriphostoma |
| Phorcys | P. dubei | Delportsrivier | Eodicynodon and Tapinocephalus A-Z. | A partial skull from the occiput (the back face of the skull) up to the orbits, including the basicranium (the floor of the skull beneath the braincase), an eroded upper surface preserving the intact pre parietal and portions of the surrounding frontals and parietal bones, with a broken left zygomatic arch and a left palatine displaced into the left orbit, | A gorgonopsid. | AelurosaurusEriphostoma |

##### Therocephalia

Therocephalians of the Abrahamskraal Formation :
| Taxa | Species | Locality | Assemblage Zone | Material | Notes | Images |
| Alopecodon | A. priscus | Zeekoegat, Prince Albert. | Tapinocephalus A-Z | A crushed partial skull and lower jaws. | A therocephalian. | |
| Alopecognathus | A. megalops | Beaufort West and Prince Albert. | Tapinocephalus A-Z. | Skull specimens. | A therocephalian. | |
| Eutheriodon | E. vandenheeveri | Modderdrift, Prince Albert. | Eodicynodon A-Z. | A partial snout and lower jaws. | A scylacosaurid therocephalian. | |
| Glanosuchus | G. macrops | Gioflok’s Fontein, near Van der Byl’s Iird in the Gouph | Eodicynodon A-Z. | A holotype consists of a partial skull. | A scylacosaurid therocephalian. | |
| Hyaenasuchus | H. whaitsi | Rietfontein | Tapinocephalus A-Z. | A weathered skull. | A therocephalian. | |
| Ictidosaurus | I. angusticeps | Beaufort West | Eodicynodon and Tapinocephalus A-Z. | A holotype preserved skull. | A scylacosaurid therocephalian. | |
| Pardosuchus | P. whaitsi | Prince Albert | Tapinocephalus A-Z. | Holotypes consist of preserved skulls. | A pristerognathinae therocephalian formally named Lycedops scholtzi. | Specimens of Pardosuchus |
| Pristerognathus | P. minor | Beaufort West and Prince Albert. | Pristerognathus A-Z. | Multiple skull specimens. | A therocephalian. | |
| Pristerognathus | P. parvus | Beaufort West and Prince Albert. | Pristerognathus A-Z. | Multiple skull specimens. | A therocephalian. | |
| Pristerognathus | P. vanderbyli | Beaufort West and Prince Albert. | Pristerognathus A-Z. | Multiple skull specimens. | A therocephalian. | |
| Pristerognathus | P. vanwyki | Beaufort West and Prince Albert. | Pristerognathus A-Z. | Multiple skull specimens. | A therocephalian. | |
| Scymnosaurus | S. ferox | Prince Albert and Vers Fontein/Jan Willem Fortein | Tapinocephalus A-Z. | Partial skull consists of snout tip, dentition, and palate. | A therocephalian therapsids. | |
| Tamboeria | T. maraisi | Prince Albert and Tamboers Fontein. | Tapinocephalus A-Z. | | A middle-sized carnivorous therocephalian | |
| Trochosuchus | T. acutus | Rietfontein and Prince Albert. | Tapinocephalus A-Z. | A fossilized skull. | A Lycosuchid therocephalian. | |
| Trochosuchus | T. intermedius | Rietfontein and Prince Albert. | Tapinocephalus A-Z. | A fossilized skull. | A Lycosuchid therocephalian. | |
| Trochosuchus | T. major | Rietfontein and Prince Albert. | Tapinocephalus A-Z. | A fossilized skull. | A Lycosuchid therocephalian. | |

#### Varanopidae

Varanopids of the Abrahamskraal Formation :
| Taxa | Species | Locality | Assemblage Zone | Material | Notes | Images |
| Anningia | A. megalops | Prince Albert | The Middle of the Tapinocephalus A-Z. | A partial skull. | A varanopid synapsid. | Elliotsmithia longiceps |
| Elliotsmithia | E. longiceps | Prince Albert | Tapinocephalus A-Z. | A holotype consists of a skull. | A small varanopid synapsid. | Elliotsmithia longiceps |
| Heleosaurus | H. scholtzi | Victoria West. | Tapinocephalus A-Z. | A preserved skeleton. | A varanopid synapsid. | Elliotsmithia longiceps |
| Microvaranops | M. parentis | Beukesplaas farm | Tapinocephalus A-Z. | A skeletal aggregation containing one grown and four immature individuals. | A varanopid synapsid. | Elliotsmithia longiceps |

## Correlation

The Abrahamskraal Formation corresponds with numerous localities abroad. Currently it is considered to correlate chronostratigraphically with the Rio do Rasto Formation from the Paraná Basin in Brazil, the Madumabisa Mudstone Formation of Zambia, the Ocher and Isheevo faunas of Russia, and to the Dashankou fauna from the Xidagou Formation of China. However, correlative dating between the Xidagou Formation and the Abrahamskraal Formation remains inconsistent and needs further study.