Traces of Storms From the PaleoArchean Found

Sedimentology of the ∼3.3 Ga upper Mendon Formation, Barberton Greenstone Belt, South Africa

Authors:

Trower et al

Abstract:

The Mendon Formation is the uppermost unit of the 3.5–3.26 Ga Onverwacht Group in the Barberton Greenstone Belt, South Africa. It consists of a cyclic stack of komatiitic volcanic units separated by thin cherty sedimentary layers. In most areas, the uppermost Mendon Formation is a sedimentary interval characterized by black chert, banded black-and-white chert, and banded ferruginous chert, although the detailed patterns of lithofacies in different sections are more complex. Previously reported zircon U/Pb ages suggest that Mendon deposition could represent more than 70 Myr of time between ∼3334 Ma and ∼3260 Ma.

This study presents sedimentological and petrographic observations of the upper Mendon Formation from across the central part of the Barberton Greenstone Belt in order to investigate sediment sources, depositional processes, and environments of sedimentation. The dominant mode of sedimentation was quiet settling of carbonaceous grains and, in the deepest sections below storm wave base, fine ferruginous material, resulting in finely laminated black and grey chert. In situ carbonaceous laminations are rare, suggesting that benthic microbial mat growth had little direct influence on deposition. The hemipelagic background deposition was punctuated by occasional inputs of fine pyroclastic debris, formation and deposition of silica granules, and reworking by infrequent storm events. Storm deposits are represented by coarse-grained, poorly-sorted intraclast breccias, some of which include distinctive intraclasts sampling lithofacies that are not observed in situ. Despite considerable lateral variability, correlative temporal trends are resolvable in many Mendon sections: there is an upward-deepening of the overall depositional setting recorded in the oldest upper Mendon sections, consistent with the previous interpretation that Mendon time was characterized by rifting (Lowe, 1994a, 1999a). Younger Mendon cycles include thick, relatively ferruginous basal sections, interpreted to reflect the deepest water deposition. These sections are capped by black chert and silicified ashes with more evidence of disturbance and reworking by storms, reflecting gradual shoaling. This sedimentological analysis is broadly consistent with previous geochemical and tectonic analyses and provides a better picture of depositional patterns during uppermost Onverwacht time, before the distinct change in tectonic regime marked by impact spherule layer S2 and the onset of Fig Tree Group orogenesis and related siliciclastic deposition.

Abdalodon diastematicus: a new Cynodont From Upper Permian South Africa

A new taxon of cynodont from the Tropidostoma Assemblage Zone (upper Permian) of South Africa, and the early evolution of Cynodontia

Author:

Kammerer

Abstract:

A new taxon of early cynodont, Abdalodon diastematicus gen. et sp. nov., is described. The new taxon is represented by a single skull from the upper Permian Tropidostoma Assemblage Zone (AZ) of the Beaufort Group (Karoo Basin, South Africa), which was previously referred to Procynosuchus delaharpeae. Abdalodon is distinguished from Procynosuchus by the presence of only four upper and three lower incisors, fewer postcanines, a well-developed depression on the lateral surface of the maxilla posterior to the canine root, a tall mandibular symphysis forming a distinct ‘chin’, a relatively short snout, and weak or absent interdigitation of sutures in the interorbital region. These features are shared with the only other Tropidostoma AZ cynodont, Charassognathus gracilis. Abdalodon is distinguished from Charassognathus by its postcanine morphology, the presence of an expanded masseteric fossa, inset postcanine tooth rows, a broader interorbital region, and proportionally shorter temporal region. Most strikingly, Abdalodon has a lengthy diastema between the canines and postcanines on both the maxilla and the dentary. Charassognathus has a short diastema between the upper canine and postcanines, but not the lowers, and diastemata are absent from the tooth rows of Procynosuchus. Phylogenetic analysis recovers Abdalodon as the sister-taxon of Charassognathus, forming a clade (Charassognathidae fam. nov.) at the base of Cynodontia. These taxa represent a previously unrecognized radiation of small-bodied Permian cynodonts. Despite their small size, the holotypes of Abdalodon and Charassognathus probably represent adults and indicate that early evolution of cynodonts may have occurred at small body size, explaining the poor Permian fossil record of the group.

PaleoArchean Crust in South Africa With Evidence of Subduction

Chronology of the oldest supracrustal sequences in the Palaeoarchaean Barberton Greenstone Belt, South Africa and Swaziland

Authors:

Kröner et al

Abstract:

Zircon age data for felsic metavolcanic rocks of the Sandspruit and Theespruit formations, the two oldest supracrustal components in the Palaeoarchaean Barberton Greenstone Belt, show that these two successions are time-equivalent and constitute one single volcanic event at ca. 3530 Ma. The Sandspruit felsic rocks are ubiquitously metasomatized, intensely deformed and intruded by, and tectonically interlayered with, ca. 3450 Ma granitoid sills that are probably part of the Theespruit Pluton. One metasomatized Sandspruit sample contains abundant metamorphic zircons with a weighted mean 207Pb/206Pb age of 3220.1±1.6 Ma, reflecting a widespread metamorphic event in parts of the eastern Kaapvaal craton in South Africa and Swaziland.

Several samples of felsic metavolcanic rocks of the Theespruit Formation confirm a previously established magmatic emplacement age of ca. 3530 Ma, but slightly older rocks up to 3552 Ma were found in the easternmost exposure of the Theespruit sequence near the South African/Swaziland border and may represent a lower lithostratigraphic level than exposed farther west.

Hf-in-zircon isotopic data for most felsic metavolcanic rocks confirm earlier results suggesting that these rocks predominantly originated from melting of a felsic continental basement, possibly related to the oldest, ca. 3660-3550 Ma components of the Ancient Gneiss Complex in Swaziland. However, several Sandspruit samples also suggest that a juvenile source was involved in their generation, perhaps a mafic underplate. We see no evidence in the geochemistry and isotopic signatures of felsic volcanic rocks of the Sandspruit and Theespruit formations for partial melting of a metabasaltic protolith and for Palaeoarchean oceanic crust that formed in connection with subduction. We rather favour a plateau-type setting on older continental crust.

How Much can we Trust Zircons? Not Much for Archean South Africa

How far can we trust provenance and crustal evolution information from detrital zircons? A south African case study

Authors:

Andersen et al

Abstract:

U–Pb and Lu-Hf data are routinely used to trace detrital zircon in clastic sediments to their original source in crystalline bedrock (the protosource), to map out paths of sediment transport, and characterize large-scale processes of crustal evolution. For such data to have a provenance significance, a simple transport route from the protosource in which the zircon formed to its final site of deposition is needed. However, detrital zircon data from Phanerozoic sedimentary cover sequences in South Africa suggest that this “source to sink” relationship has been obscured by repeated events of sedimentary recycling. Phanerozoic sandstones (Cape Supergroup, Karoo Supergroup, Natal Group, Msikaba Formation) and unconsolidated, Cenozoic sands in South Africa share major detrital zircon fractions of late Mesoproterozoic (940–1120 Ma, εHf ≈ 0 to + 15) and Neoproterozoic age (470–720 Ma, εHf ≈ − 10 to + 8). A Permian age fraction (240–280 Ma, εHf ≈ − 8 to + 5) is prominent in sandstones from the upper part of the Karoo Supergroup. All of these sequences are dominated by material derived by recycling of older sedimentary rocks, and only the youngest, late Palaeozoic fraction has a clear provenance significance (Gondwanide orogen). The virtual absence of Archaean zircon is a striking feature in nearly all suites of detrital zircon studied in the region. This indicates that significant events in the crustal evolution history of southern African and western Gondwana are not represented in the detrital zircon record. South Africa provides us with a record of recycling of cover sequences throughout the Phanerozoic, and probably back into the Neoproterozoic, in which the “sink” of one sedimentary cycle will act as the “source” in subsequent cycles. In such a setting, detrital zircon may give information on sedimentary processes rather than on provenance.

A Revision of Whaitsiid Therocephalian Theriognathus From Late Permian South Africa

Revision of the first therocephalian, Theriognathus Owen (Therapsida: Whaitsiidae), and implications for cranial ontogeny and allometry in nonmammaliaform eutheriodonts

Authors:

Huttenlocker et al

Abstract:

Historically, the whaitsiid therocephalian Theriognathus Owen was one of the earliest described nonmammalian therapsids, its morphology helping to link phylogenetically the Paleozoic synapsids of North America and southern Africa to their mammalian successors. However, decades of taxonomic over-splitting and superficial descriptions obscured the morphologic diversity of the genus, hindering its utility as a study system for the evolution of synapsid cranial function as well as its biostratigraphic significance in the Late Permian of southern Africa. Here, we revise the status and provenance of all the known specimens of Theriognathus from South Africa, Tanzania, and Zambia. We present both qualitative and quantitative support for the presence of a single morphospecies as proposed by some authors. Proportional differences in skulls that were previously ascribed to different morphotypes (‘Aneugomphius,’ ‘Notosollasia,’ ‘Moschorhynchus,’ and ‘Whaitsia’) are largely size-related and allometric trends are considered here in the context of jaw function and prey prehension. Our results suggest that the single species, Theriognathus microps, represented one of the most abundant Late Permian therocephalians in southern Africa and is consequently a potentially useful biostratigraphic marker for the upper Cistecephalus-lower Dicynodon Assemblage Zone transition (i.e., late Wuchiapingian). The wide range of preserved sizes in conjunction with recent paleohistological evidence supports that individuals spent much of their lives in an actively-growing, subadult phase. Later Dicynodon Assemblage Zone records (e.g., upper Balfour Formation) are unconfirmed as the genus was likely replaced by other theriodont predators (e.g., Moschorhinus) leading up to the Permo-Triassic boundary in the Karoo Basin of South Africa.

Middle Permian Dicynodont Chelydontops altidentalis is a Junior Synonym of Brachyprosopus broomi

A reevaluation of Brachyprosopus broomi and Chelydontops altidentalis, dicynodonts (Therapsida, Anomodontia) from the middle Permian Tapinocephalus Assemblage Zone of the Karoo Basin, South Africa

Authors:

Angielczyk et al

Abstract:

Brachyprosopus broomi was described in 1937 based on a specimen from the Tapinocephalus Assemblage Zone (Karoo Basin, South Africa), but it was largely overlooked by subsequent workers. We have identified several new specimens that show that Brachyprosopus is a valid taxon. An autapomorphy for the taxon is a curled lateral edge of the squamosal that forms a lateral wall of the external adductor fossa. Other important characters are absence of anterior median palatal ridges; maxillary tooth rows bounded laterally by a shelf; unfused vomers; raised margins of the interpterygoid vacuity; broad intertemporal region; pineal boss; dentary tables; and a long, wide posterior dentary sulcus that extends posterior to the dentary teeth. Chelydontops altidentalis is a junior synonym of B. broomi. A phylogenetic analysis places Brachyprosopus among basal dicynodonts, not as a close relative of Endothiodon. It is noteworthy that some characters, such as well-developed medial maxillary tooth rows and the shape of the palatines, are shared by Brachyprosopus, Pristerodon, Endothiodon, and Niassodon, hinting that a final resolution of relationships among toothed dicynodonts remains to be achieved. Most Brachyprosopus specimens are from the upper Abrahamskraal Formation (Moordenaars and Karelskraal members). One specimen is from low in the Koonap Formation, just above the lowermost maroon mudrocks of the Beaufort Group, and an exact correlation between this level and the strata of the Abrahamskraal Formation is uncertain. Therefore, it is likely that the stratigraphic range of Brachyprosopus extends throughout the Tapinocephalus zone and possibly down into the Eodicynodon Assemblage Zone.

Late Permian Tuskless Geikiid Cryptodont Dicynodont Pelanomodon Redescribed, Shows Sexual Dimorphism

Redescription of the geikiid Pelanomodon (Therapsida, Dicynodontia), with a reconsideration of ‘Propelanomodon’

Authors:

Kammerer et al

Abstract:

Cryptodont dicynodonts are some of the most abundant therapsid taxa in the upper Permian fossil record. Despite extensive taxonomic study of these families, the species diversity of geikiid cryptodonts remains problematic, particularly for the set of edentulous taxa in the genera Pelanomodon, Propelanomodon, and Geikia. Here, all known specimens of tuskless geikiid dicynodonts from the upper Permian Karoo Basin of South Africa are reevaluated. The genus Pelanomodon is redescribed based on a series of skulls representing a range of sizes. All tuskless geikiids from the Karoo Basin are considered to represent a single species (Pelanomodon moschops) that exhibited cranial dimorphism as adults. The nominal species Pe. moschops and Pe. rubidgei differ only in degree of facial boss development and are most parsimoniously interpreted as sexual dimorphs. Propelanomodon is considered to represent the juvenile morphotype of Pelanomodon moschops, as indicated by the geographic and stratigraphic overlap of the two taxa, the lack of any small skulls of the Pelanomodon morphotype in well-sampled localities, and the presence of specimens of intermediate size and morphology. ‘Propelanomodon’ specimens are distinctive among juvenile dicynodonts in having a significantly narrower intertemporal region than adults. Analysis of intertemporal width relative to total skull size in Pelanomodon and the abundant cryptodont taxa Aulacephalodon, Oudenodon, and Tropidostoma suggests that Pelanomodon had a unique growth trajectory. Based on available stratigraphic data, Pelanomodon was restricted to the uppermost Permian Daptocephalus Assemblage Zone of the South African Beaufort Group and was a victim of the end-Permian mass extinction.

Evidence for Cavity-dwelling Microbial Life (coelobionts) From PaleoArchean Tidal Flats

Evidence for cavity-dwelling microbial life in 3.22 Ga tidal deposits

Authors:

Homann et al

Abstract:

Cavities are considered plausible and favorable habitats for life on early Earth. In such microenvironments, organisms may have found an adequate protection against the intense ultraviolet radiation that characterized the Archean ozone-free atmosphere. However, while there is clear evidence that benthic life existed in the Paleoarchean, the oldest traces of cavity-dwelling microbes (coelobionts) have been found in Neoarchean rocks. Here we present the results of a detailed investigation of early silicified cavities occurring in the oldest well-preserved siliciclastic tidal deposits, the 3.22 Ga Moodies Group of the Barberton Greenstone Belt (South Africa). Downward-growing microstromatolitic columns composed of kerogenous laminae are commonly present in planar, bedding-parallel, now silica-filled cavities that formed in sediments of the peritidal zone. In-situ δ13CPDB (PDB—Peedee belemnite) measurements of the kerogen range from –32.3‰ to –21.3‰ and are consistent with a biogenic origin. Scanning electron microscopy analysis of the silicified cavities shows well-preserved chains of cell-sized molds that are interpreted as fossil filamentous microorganisms. The geological context, the morphology of the microstromatolites, the δ13C composition of the kerogen, and the presence of microfossils all suggest that a microbial community inhabited the cavities. These results extend the geological record of coelobionts by ∼500 m.y., supporting the view that cavities were among the first ecological niches to have been occupied by early microorganisms.

There Were Distinct Major Papionin Primate Clades in the Pliocene/Pleistocene South Africa

Cercopithecoid humeri from Taung support the distinction of major papionin clades in the South African fossil record

Authors:

Gilbert et al

Abstract:

Associated cercopithecoid postcrania are rare in the Plio-Pleistocene fossil record, particularly in the case of South African karst cave sites. However, as clear postcranial differences between major papionin clades have been documented, it should be possible to assign isolated papionin postcrania to the Cercocebus/Mandrillus and Papio/Lophocebus/Theropithecus groups wherever sufficient anatomy is preserved. Here, we demonstrate that two partial humeri preserved at Taung, UCMP 56693 and UCMP 125898, are most likely attributable to the Cercocebus/Mandrillus and Papio/Lophocebus/Theropithecus clades, respectively. Univariate analyses (ANOVAs and t-tests) and multivariate analyses (discriminant function analyses) of humeral features, combined with a phylogenetic analysis of 24 humeral characters, all support our assessment. Given that the overwhelming number of craniodental specimens at Taung are attributable to two papionin taxa, Procercocebus antiquus (a member of the Cercocebus/Mandrillus clade) and Papio izodi (a purported fossil species of the modern genus Papio), we assign UCMP 56693 to Pr. antiquus and UCMP 125868 to P. izodi with a high degree of confidence. Implications for cercopithecoid evolution and biogeography are discussed, with a particular emphasis on these two fossil taxa.

Homo naledi may Date From the Gelasian Pleistocene Quaternary (2 Million Years ago)

Estimating the age and affinities of Homo naledi

Author:

Thackeray

Extract:

Recent discoveries of more than 1500 hominin fossils from the site of Rising Star in the South African Cradle of Humankind, attributed to a new species (Homo naledi), have attracted global interest. As yet no secure date for this extraordinary material has been obtained, and the relationship of this species to other Plio-Pleistocene taxa has been greatly debated in the media. Here I report results of morphometric analyses that may facilitate an assessment of the age and affinities of crania attributed to H. naledi.

pop sci write up.

Late Permian Cynodont Cynosaurus Lacked a Pineal eye, may Have Been Endothermic

Physiological implications of the abnormal absence of the parietal foramen in a late Permian cynodont (Therapsida)

Authors:

Benoit et al

Abstract:

The third eye (pineal eye), an organ responsible for regulating exposure to sunlight in extant ectotherms, is located in an opening on the dorsal surface of the skull, the parietal foramen. The parietal foramen is absent in extant mammals but often observed in basal therapsids, the stem-group to true mammals. Here, we report the absence of the parietal foramen in a specimen of Cynosaurus suppostus, a Late Permian cynodont from South Africa (SA). Comparison with Procynosuchus delaharpeae, a contemporaneous non-mammalian cynodont from SA, demonstrates that the absence of this foramen is an abnormal condition for such a basal species. Because seasonality was marked during the Late Permian in SA, it is proposed that the third eye was functionally redundant in Cynosaurus, possibly due to the acquisition of better thermoregulation or the evolution of specialized cells in the lateral eyes to compensate for the role of the third eye.

Homo naledi: a new Member of the Homo Genus who Buried its Dead

An international research team, which includes NYU anthropologists Scott Williams and Myra Laird, has discovered a new species of a human relative. Homo naledi, uncovered in a cave outside of Johannesburg, South Africa, sheds light on the diversity of our genus and possibly its origin.

"This discovery is unprecedented in the sheer number of hominins collected from such a small area in the virtual absence of other animal remains," says Williams, an assistant professor in NYU's Department of Anthropology. "That makes this site unique. Moreover, the announcement describes only the tip of the iceberg of analyses that will come, and we hope that is also true of the cave itself and the material that it still holds."

The team's findings, which are published in two papers in the journal eLife, were announced by South Africa's University of the Witwatersrand, the National Geographic Society, and the South African National Research Foundation.

The discovery also indicates that H. naledi intentionally deposited bodies of its dead in a remote cave chamber--behaviors previously thought limited to humans.

link.

2nd link. 

3rd link.

open access paper link.

Age uncertain.  Could be as old as early Pleistocene (2.1MYA) or as young as late Pleistocene (100kya)

John Hawks is the second author.  When he puts up a post on it, I'll link, too.  Someone ought to give him a hard time and ask if this isn't a diseased Homo sapiens.

The Curious Case of Tribrachidium "Boneyards" From Ediacaran NeoProterozoic South Africa

Paleoecology of the enigmatic Tribrachidium: New data from the Ediacaran of South Australia

Authors:

Hall et al

Abstract:

Tribrachidium is a monospecific genus of the Ediacara biota found globally. In the Ediacara Member of the Rawnsley Quartzite, Flinders Ranges of South Australia, the spatial distribution of Tribrachidium across the seafloor is best described as patchy. Although Tribrachidium is the dominant fossil on two of the twenty-six beds currently excavated and is present in large numbers on another, the genus most commonly occurs as no more than a handful of specimens on a bed. Tribrachidium size frequency distributions of each of the three beds with more than 5 specimens are all statistically distinguishable from one another. Additionally, the size range on any given bed is smaller than the overall size range observed for the genus. These patterns suggest that these organisms lived in populations composed of single generations. The beds with numerous Tribrachidium come from different facies and are characterized by the presence of dissimilar mixes of taxa and textured organic surfaces, indicating that Tribrachidium was a generalist, able to adapt to a variety environments. Uniquely, the base or internal structure of Tribrachidium is also found preserved in both positive and negative relief as a sequence of concentric ridges on beds where Tribrachidium is the dominant genus. The most parsimonious explanation for the presence of these concentric ridge fossils is that they are the fossilized form of a Tribrachidium preserved when the organism was buried upside-down, flipped over, or dead and partially decayed prior to burial.

Intraspecies Combat Probably Practiced by Roadian Permian Anomodonts Tiarajudens & Anomocephalus

Tiarajudens eccentricus and Anomocephalus africanus, two bizarre anomodonts (Synapsida, Therapsida) with dental occlusion from the Permian of Gondwana

Authors:

Cisneros et al

Abstract:

Anomodontia was a highly successful tetrapod clade during the Permian and the Triassic. New morphological information regarding two bizarre basal anomodonts is provided and their palaeoecological significance is explored. The osteology of the recently discovered Tiarajudens eccentricus Cisneros et al. 2011, from the Brazilian Permian, is described in detail. The taxon exhibits unusual postcranial features, including the presence of gastralia. Additional preparation and computed tomography scans of the holotype of Anomocephalus africanus Modesto et al. 1999 discovered in the Karoo Basin of South Africa allow a reappraisal of this genus. Anomocephalus is similar to Tiarajudens with regard to several traits, including a battery of large, transversally expanded, palatal teeth. Molariform teeth are present in the mandible of the African taxon, providing additional insight into the function of the earliest tooth-occlusion mechanism known in therapsids. At least two waves of tooth replacement can be recognized in the palate of Anomocephalus. The outsized, blade-like caniniforms of the herbivorous Tiarajudens allow several non-exclusive ecological interpretations, among which we favour intraspecific display or combat. This behaviour was an alternative to the head-butting practised by the contemporary dinocephalians. Combat specializations that are considered typical of Cenozoic herbivores likely evolved during the Middle Permian, at the time the first communities with diverse, abundant tetrapod herbivores were being assembled.

Guadalupian Mass Extinction Confirmed in Karoo Basin, South Africa

When and how did the terrestrial mid-Permian mass extinction occur? Evidence from the tetrapod record of the Karoo Basin, South Africa

Authors:

Day et al

Abstract:

A mid-Permian (Guadalupian epoch) extinction event at approximately 260 Ma has been mooted for two decades. This is based primarily on invertebrate biostratigraphy of Guadalupian–Lopingian marine carbonate platforms in southern China, which are temporally constrained by correlation to the associated Emeishan Large Igneous Province (LIP). Despite attempts to identify a similar biodiversity crisis in the terrestrial realm, the low resolution of mid-Permian tetrapod biostratigraphy and a lack of robust geochronological constraints have until now hampered both the correlation and quantification of terrestrial extinctions. Here we present an extensive compilation of tetrapod-stratigraphic data analysed by the constrained optimization (CONOP) algorithm that reveals a significant extinction event among tetrapods within the lower Beaufort Group of the Karoo Basin, South Africa, in the latest Capitanian. Our fossil dataset reveals a 74–80% loss of generic richness between the upper Tapinocephalus Assemblage Zone (AZ) and the mid-Pristerognathus AZ that is temporally constrained by a U–Pb zircon date (CA-TIMS method) of 260.259 ± 0.081 Ma from a tuff near the top of the Tapinocephalus AZ. This strengthens the biochronology of the Permian Beaufort Group and supports the existence of a mid-Permian mass extinction event on land near the end of the Guadalupian. Our results permit a temporal association between the extinction of dinocephalian therapsids and the LIP volcanism at Emeishan, as well as the marine end-Guadalupian extinctions.

First Evidence of a Post Wildfire Debris Flow From the Valanginian (?) Cretaceous Algoa Basin

Lower Cretaceous deposit reveals first evidence of a post-wildfire debris flow in the Kirkwood Formation, Algoa Basin, Eastern Cape, South Africa

Authors:

Muir et al

Abstract:

The Algoa Basin is an onshore rift basin filled by an Upper Mesozoic non-marine and shallow marine sedimentary sequence. The middle unit of this clastic succession is assigned to the Lower Cretaceous Kirkwood Formation, known to host a wealth of plant and animal fossils together with poorly documented lignites, amber and charcoal clasts. This study is motivated by the growing interest in the impact of wildfires on the palaeoenvironment during the high-oxygen, Cretaceous world. It has been hypothesised that frequent and severe Cretaceous wildfires triggered large-scale non-marine denudation events, altering the sedimentation dynamics and influencing the evolution of ecosystems. In order to investigate this phenomenon, charcoal-bearing sedimentary rocks and plant fossil assemblages of the Kirkwood Formation have been studied at the Bezuidenhouts River locality, ∼50 km north of Port Elizabeth (Eastern Cape, South Africa).

Detailed field observations of the sedimentary facies suggest that deposition occurred in a meandering fluvial environment with mature, vegetated floodplains. Depositional trends within a charcoal-rich bed (i.e., stratification, flattening and decrease in charcoal clast size down-current) indicate that a charcoal-rich debris flow, linked to a post-wildfire flood event, became diluted by fluvial flow. Palaeocurrent indicators (e.g., orientation of fossil logs) suggest unidirectional currents from SW to NE, which are somewhat inconsistent with the previously reported regional palaeocurrent directions in the Kirkwood Formation.

To gain insights into the fire-influenced dynamics of the Early Cretaceous ecosystems, the macro-plant fossil assemblages of the Kirkwood Formation were considered, with reference to the responses of modern plant analogues to wildfire. Of the plant orders reported from macrofossils of the Kirkwood Formation, the Cycadales, Pinales and Filicales, are known to have produced large woody or fibrous trunks and stems, or in the case of the Bennettitales more densely branched, divaricate architectures, and are likely to have provided the bulk of fuel for wildfires, with fern elements dominating groundcover niches. The particular role of these plants in the Early Cretaceous wildfire palaeoecology of the Algoa Basin is a topic for an ongoing study, but the Bezuidenhouts River locality appears to record the aftermath of a severe crownfire that led to mass tree mortality.

Eriphostoma microdon: new Specimens of the Oldest Permian Gorgonopsid Found

New information on the morphology and stratigraphic range of the mid-Permian gorgonopsian Eriphostoma microdon Broom, 1911

Authors:

Kammerer et al

Abstract:

New specimens of the oldest gorgonopsian taxon Eriphostoma microdon from the Pristerognathus Assemblage Zone (AZ) of South Africa significantly improve our understanding of the anatomy of this taxon. The new specimens consist of nearly complete skulls and lower jaws and allow for a more complete diagnosis of Eriphostoma than was possible based on the poorly preserved holotype. In addition to the characteristic palatal dentition and delta-shaped palatine bosses previously recognized for Eriphostoma, this taxon can be diagnosed by the presence of three close-packed upper postcanines occupying an indented margin of the maxilla, a large, tetragonal-to-rounded preparietal bone, and large, paired interorbital depressions expanding outwards in front of the pineal boss. The revised diagnosis permits Eoarctops vanderbyli, Galesuchus gracilis, and Scylacognathus parvus to be synonymized with Eriphostoma microdon, as previously suspected. Among gorgonopsians, Eriphostoma is most similar to Aelurosaurus and Gorgonops, although these similarities are likely plesiomorphic for Gorgonopsia. Eriphostoma ranges from the Tapinocephalus AZ (where it is the only valid gorgonopsian known from the Karoo Basin) through the Pristerognathus AZ (where it co-occurs with Gorgonops).

Emydopoid Dicynodont Digalodon rubidgei Redescribed

Redescription of Digalodon rubidgei, an emydopoid dicynodont (Therapsida, Anomodontia) from the Late Permian of South Africa. (pdf)

Authors:

Fröbisch et al

Abstract:

The Late Permian dicynodont Digalodon rubidgei Broom and Robinson, 1948, is redescribed based on reanalysis of the holotype and newly recognized referable specimens. Digalodon can be diagnosed by the presence of a long “beak” sharply demarcated from the caniniform process; an extremely tall zygomatic ramus of the squamosal, with a thickened, “folded-over” dorsal margin; raised parietal “lips” along the lateral edges of the pineal foramen; and a broad posterolateral expansion of the parietal, excluding the postorbital from the back of the skull roof. Inclusion of Digalodon in a recent analysis of anomodont phylogeny recovers it as a kistecephalian emydopoid, specifically as the sister taxon to the clade containing the remaining kistecephalians. Four definite specimens of Digalodon are known, but several additional specimens lacking tusks, the swollen pineal “lips”, and a thickened zygoma may represent sexually dimorphic females or juveniles. Specimens of Digalodon are restricted to the central portion of the Karoo Basin, in the area around Graaff-Reinet, and are part of a characteristic fauna probably representing a limited time span.

Pliocene Neogene Chameleon Fossils Found in South Africa

Morphometric analysis of chameleon fossil fragments from the Early Pliocene of South Africa: a new piece of the chamaeleonid history

Authors:

Dollion et al

Abstract:

The evolutionary history of chameleons has been predominantly studied through phylogenetic approaches as the fossil register of chameleons is limited and fragmented. The poor state of preservation of these fossils has moreover led to the origin of numerous nomen dubia, and the identification of many chameleon fossils remains uncertain. We here examine chameleon fossil fragments from the Early Pliocene Varswater formation, exposed at the locality of Langebaanweg “E” Quarry along the southwestern coast of South Africa. Our aim was to explore whether these fossil fragments could be assigned to extant genera. To do so, we used geometric morphometric approaches based on microtomographic imaging of extant chameleons as well as the fossil fragments themselves. Our study suggests that the fossils from this deposit most likely represent at least two different forms that may belong to different genera. Most fragments are phenotypically dissimilar from the South African endemic genus Bradypodion and are more similar to other chameleon genera such as Trioceros or Kinyongia. However, close phenetic similarities between some of the fragments and the Seychelles endemic Archaius or the Madagascan genus Furcifer suggest that some of these fragments may not contain enough genus-specific information to allow correct identification. Other fragments such as the parietal fragments appear to contain more genus-specific information, however. Although our data suggest that the fossil diversity of chameleons in South Africa was potentially greater than it is today, this remains to be verified based on other and more complete fragments.

Evidence of a Large Asteroid/Comet Impact During the Siderian PaleoProterozoic

First detection of extraterrestrial material in ca. 2.49 Ga impact spherule layer in Kuruman Iron Formation, South Africa

Authors:

Simonson et al

Abstract:

Thin layers rich in formerly molten spherules interpreted as distal ejecta from large impacts by extraterrestrial bodies have been found in 8 stratigraphic units deposited between ca. 2.63 Ga and 2.49 Ga and attributed to a minimum of 4 separate impacts. Here we report geochemical evidence of extraterrestrial material in the only one of these spherule layers where it has not been previously reported, the Kuruman spherule layer (KSL) in the Kuruman Iron Formation, a banded iron formation (BIF) in the Griqualand West Basin (South Africa). We identified the KSL in 3 drill cores separated by as much as ~350 km and analyzed 2 core samples that have a mean Ir concentration of ~12.9 ppb and nearly chondritic interelement ratios of platinum group elements Ir, Ru, Pt, and Rh. This suggests that the samples contain ~1%–3% by mass extraterrestrial material even though the spherules are highly diluted by ambient sediment. Our geochemical data strongly support the correlation of the KSL with the Dales Gorge spherule layer (DGSL) in a penecontemporaneous BIF in the Hamersley Basin (Western Australia). The KSL and DGSL are close matches in terms of major and various trace element contents and the DGSL has a comparable Ir content of ~11.5 ppb. Therefore it is very likely the KSL and DGSL are distal ejecta from a ca. 2.49 Ga impact by a single extraterrestrial object greater than 10 km across. The lack of any significant changes in the stratigraphic succession in either basin also implies that large impacts alone are not sufficient to cause long-term changes in Earth's surface environments.