Lopingian Permian Niger had a Wildly Seasonal Arid Climate With Water Inundations Like the African Namib Desert and Australian Lake Eyre Basin

Biological and physical evidence for extreme seasonality in central Permian Pangea

Authors:

Looy et al

Abstract:

Climate models indicate increased desertification in the continental interior of Pangea during the Permian, which would have affected the composition of the flora and fauna. We present a multi-proxy paleoenvironmental reconstruction of a terrestrial ecosystem in central Pangea of Lopingian age. The reconstruction is based on biological and physical data from the Moradi Formation, located in the Tim Mersoi Basin, northern Niger. Paleosols and sedimentological evidence indicate that the prevailing climate was semi-arid to very arid with marked intervals of high water availability. Carbon stable isotope data from organic matter and paleosols suggest that both the soil productivity and actual evapotranspiration were very low, corresponding to arid conditions. Histological analysis of pareiasaur bones shows evidence of active metabolism and reveals distinct growth marks. These interruptions of bone formation are indicative of growth rhythms, and are considered as markers for contrasting seasonality or episodic climate events. The macrofossil floras have low diversity and represent gymnosperm-dominated woodlands. Most notable are ovuliferous dwarf shoots of voltzian conifers, and a 25-m long tree trunk with irregularly positioned branch scars. The combined biological and physical evidence suggests that the Moradi Formation was deposited under a generally arid climate with recurring periods of water abundance, allowing for a well-established ground water-dependent ecosystem. With respect to its environment, this system is comparable with modern ecosystems such as the southern African Namib Desert and the Lake Eyre Basin in Australia, which are discussed as modern analogues.

 

Bunostegos akokanensis: a Unique Nearly Parasagittal Pareiasaur From Upper Permian Niger

The vertebrate fauna of the upper Permian of Niger—IX. The appendicular skeleton of Bunostegos akokanensis (Parareptilia: Pareiasauria)

Authors:

Turner et al

Abstract:

Pareiasaurs were a group of herbivorous reptiles that lived during the middle to late Permian (˜265–252 Ma) in what is modern-day Europe, Asia, South America, and Africa. Field work in the Moradi Formation of northern Niger has produced multiple elements of the appendicular skeleton of the pareiasaur Bunostegos akokanensis. The considerable size disparity and morphological variation among the elements suggest that they represent ontogenetic stages ranging from relatively juvenile to adult. Here we present the first description of the scapulocoracoid, humerus, radius, ulna, pelvis, and femur of Bunostegos as well as some of the first ontogenetic data for postcranial osteology in pareiasaurs. As with the skull, numerous postcranial autapomorphies characterize Bunostegos, including laterally originating acromion process of the scapula; radius and ulna with continuous articular surface on humerus; paired crests on the olecranon process; ulna longer than humerus; pinched posterior margin of the acetabular rim; robust pelvic symphysis extending the length of the puboischiatic plate; lack of a distinct postaxial flange of the femur; and an elaborated femoral lateral condyle wrapping over the medial condyle. We incorporated data from the appendicular skeleton of Bunostegos into a revised phylogenetic analysis of pareiasaur relationships. The results of this analysis corroborate previous cranial analyses that place Bunostegos between Guadalupian taxa and the Lopingian velosaur subclade. Interestingly, several aspects of its postcranial anatomy suggest that Bunostegos possessed relatively upright forelimb posture, which would be unique among pareiasaurs and possibly Permian amniotes as a whole.

Evidence of a Tropical wet Desert From Late Permian Niger

Sedimentology and vertebrate taphonomy of the Moradi Formation of northern Niger: A Permian wet desert in the tropics of Pangaea

Authors:

Smith et al

Abstract:

Pangaean palaeogeographic models place the Tim Mersoi basin of northern Niger in a 5000 km wide corridor between Gondwana and Laurasia approximately 15 degrees south of the palaeoequator. Late Permian palaeoclimate models position this basin between tropical summerwet to the north and desert to the south. Recent investigations of the fossil vertebrates and palaeosols in the late Permian (Lopingian) Moradi Formation confirm that the climate was warm and hyperarid with highly seasonal monsoonal rainfall. Possibly as a result of these unusual “wet desert” conditions the tetrapod fauna shows a high degree of endemism. This study tests existing palaeoclimate models by providing additional data on sedimentary environments and vertebrate taphonomic processes. The Moradi red bed sequences accumulated in a gently subsiding sag basin to the west of the tectonically active Massif de l'Aïr. Low angle gravelly alluvial fans prograded westward from the massif and at times impinged on a large stable northward flowing meandering channel system. The interchannel mudrock sequences are over-thickened by the accumulation of loessic silts and preserve isolated skull and post crania of amphibians (Nigerpeton and Saharastega) as well as semi-articulated captorhinids (Moradisaurus). Detailed surface mapping of a fossil-rich exposure revealed an anastomosed network of loess-filled distributary channels incised into the floodplain mudrocks. This provided a locus for the accumulation and rapid burial of at least 15 associated skeletons of the pareiasaurian Bunostegos. Semi-permanent ponds are evidenced by patches of fissile red mudstone containing rare bivalves and spiral coprolites. In the distal floodplains away from the main river channels, the combination of a generally high groundwater table, warm mean annual temperatures and deflation of fines from the floodplain surface promoted the formation of gypsiferous palaeosols and endpoint playa lakes. Carbonate-rich mud accumulated around the lake margins and provided ideal conditions for the imprinting and preservation of tetrapod trackways.

New Theropod Remains From Middle Jurassic Niger

New theropod remains from the Tiourarén Formation (?Middle Jurassic, Niger) and their bearing on the dental evolution in basal tetanurans

Authors:

Serrano-Martínez et al

Abstract:

A fragment of a maxilla and isolated theropod teeth from the (?) Middle Jurassic Tiourarén Formation are described. The specimens come from Tadibene, in the rural community of Aderbissinat, Thirozerine Department, Agadez Region, Niger. They were identified through direct comparison with teeth previously described in the literature as well as on the basis of discriminant and morphometric analyses. Our results suggest they belong to Ceratosauridae, Megalosauridae, and the oldest representatives of Spinosauridae. The analyzed sample shows some uncommon characters, such as spinosaurid-like ornamentation in megalosaurid-like teeth, or spinosaurid-like teeth with a low number of denticles, which sheds light on tooth morphology and dental evolution in basal tetanurans and early spinosaurids.

China in Africa: The $1 Billion Loan to Niger

Niger has accepted a controversial $1 billion loan from the Export-Import Bank of China (China Exim Bank) to finance development projects, the West African nation's planning minister said Tuesday.

Repayment of the 25-year loan will start in eight years' time "thanks to resources from the sale of oil being produced" by China National Petroleum Corporation (CNPC) in the east of the country, Amadou Boubacar Cisse announced.

The agreement, the conditions of which Cisse said were "very favourable", was signed in China on September 30.

Details were not immediately available, but typically China Exim Bank loans require the borrower nation to allocate work and equipment contracts for the project to Chinese companies.

link.

Updated Pareiasaur Phylogeny courtesy of Bunestegos

re earlier post on Bunestegos.

Bunostegos: a Desert Dwelling Relic Pareiasaur From the Late Permian Niger

During the Permian era, the Earth was dominated by a single supercontinent called Pangea – "All-Earth". Animal and plant life dispersed broadly across this land, as documented by identical fossil species found on multiple modern continents. But a new study published in the Journal of Vertebrate Paleontology supports the idea that there was an isolated desert in the middle of Pangea with a fauna all its own.

Roaming this desert in what is now northern Niger was a very distinctive creature known as a pareiasaur. Pareiasaurs were large, herbivorous reptiles that were common across Pangea during the Middle and Late Permian, about 266-252 million years ago. "Imagine a cow-sized, plant-eating reptile with a knobby skull and bony armor down its back," said lead author Linda Tsuji. The newly discovered fossils belong to the aptly-named genus Bunostegos, which means "knobby [skull] roof."

Most pareiasaurs had bony knobs on their skulls, but Bunostegos sported the largest, most bulbous ones ever discovered. In life, these were probably skin-covered horns like those on the heads of modern giraffes. Although at first blush these features seem to suggest that Bunostegos was an evolutionarily advanced pareiasaur, it also had many primitive characteristics. Tsuji's analysis showed that Bunostegos was actually more closely related to older and more primitive pareiasaurs, leading to two conclusions: first, that its knobby noggin was the result of convergent evolution, and second, that its genealogical lineage had been isolated for millions of years.

So how do you isolate a population of cow-sized reptiles? Though there were no fences in the Permian, climatic conditions conspired to corral Bunostegos – along with several other reptiles, amphibians, and plants – and keep them constrained to the central area of the supercontinent. "Our work supports the theory that central Pangea was climatically isolated, allowing a unique relict fauna to persist into the Late Permian," said Christian Sidor, another author of the paper. This is surprising because areas outside this central region show fossil evidence of regular faunal interchange.

Geological data also show that central Pangea was hyperarid (extremely dry), effectively discouraging some animals from passing through, while keeping those within from venturing out. The long period of isolation under these parched conditions gave Bunostegos lineage time to evolve its unique anatomical features.

Paleontologist Gabe Bever, who was not involved with the study, said "Research in these lesser-known basins is critically important for meaningful interpretation of the Permian fossil record. Our understanding of the Permian and the mass extinction that ended it depends on discovery of more fossils like the beautifully bizarre Bunostegos."

Paper link later.