The age of Madumabisa (Zambia) Fossil Vertebrates From Permian

Resolving the age of Madumabisa fossil vertebrates: Palynological evidence from the mid-Zambezi Basin of Zambia

Authors:

Barbolini et al

Abstract:

Age estimates for Permian rocks in the mid-Zambezi Basin of Zambia have thus far yielded ambiguous results. Previously studied palynoassemblages from the Madumabisa Formation resemble spore-pollen suites from both the Cistecephalus Zone of North Luangwa (Lopingian) and the palynological Assemblage Sub-Zone IV H of Zimbabwe, proposed as Guadalupian. In order to improve age estimates and refine the biostratigraphy of the Madumabisa Formation, this formation together with the underlying Gwembe Formation, were sampled for palynomorphs. Assemblages from the Gwembe Formation are dominated by trilete spores with less common striate and non-striate bisaccate pollen, whereas the overlying Madumabisa Formation palaeoflora is composed predominantly of striate bisaccates. Ferns, pteridosperms, lycopods, sphenophytes, glossopterids and conifers are represented in the palynofloras. The upper Gwembe Formation palynoassemblage can be correlated with the Didecitriletes ericianus Zone of Backhouse (1991), the Guttulapollenites hannonicus–Protohaploxypinus rugatus Zone (Zone VI) of Aitken (1998), Assemblage Zone III of the mid-Zambezi Basin, Zimbabwe and Biozone KK 3 in the Kalahari Karoo Basin, Botswana, suggesting a Guadalupian (Wordian–Capitanian) age. The upper Madumabisa Formation palynoassemblage can be placed in the upper Dulhuntyispora parvithola Zone of Backhouse (1991)/APP5 of Price (1997), dated as Wuchiapingian (Lopingian) and correlates with Assemblage 2 of the Moatize–Minjova Basin, Mozambique and the McKinnon Member palynofloras of East Antarctica. It also resembles Daptocephalus (formerly Dicynodon) Assemblage Zone palynofloras of the lower and middle Balfour Formation in the Karoo Basin, South Africa, and is suggested to be Lopingian (Wuchiapingian–Changhsingian) in age. Although these palynological assemblages place lower and upper age constraints on Madumabisa Formation vertebrate fossils, uncertainty remains as to the exact correlation between the Madumabisa vertebrate assemblages and the assemblage zones of the main Karoo Basin.

Mupashi migrator: a new Karenitid Therocephalian From Upper Permian Zambia

The first karenitid (Therapsida, Therocephalia) from the upper Permian of Gondwana and the biogeography of Permo-Triassic therocephalians

Authors:

Huttenlocker et al

Abstract:

Therocephalians were an ecologically diverse group of therapsids whose long stratigraphic record and widespread distribution during Permian and Triassic times make them important for understanding biogeographic patterns during a major faunal transition. Here, we describe a new therocephalian, Mupashi migrator gen. et sp. nov., from the upper Madumabisa Mudstone Formation (upper Permian) of Zambia's Luangwa Basin. The specimen has a long snout with a maxilla–vomerine contact on the hard palate, a high antecanine tooth count and numerous postcanines, and a conspicuous boss on the dentary angle whose structure is identical to that of the Russian baurioid Karenites. Additional endocranial anatomy, including palatal and braincase features, are revealed by high-resolution X-ray computed tomography and described in detail in light of the growing availability of tomographic data for therapsids. A phylogenetic analysis of 56 therapsid taxa and 136 cranial and postcranial characters recovers Mupashi as the sister taxon to Karenites, placing the pair between basal ictidosuchid-grade baurioids and the later Triassic bauriamorphs. Parsimony optimizations of geographic occurrences are ambiguous regarding the origination centers of therocephalian subclades. However, the patterns are suggestive of either (1) rapid, early dispersal events of Eutherocephalia and its major subgroups from a Laurasian center during the early–late Permian or, more likely, (2) within-province diversifications with occasional dispersal events occurring between provinces. Regardless, these associations strengthen the hypothesis that unknown but effective dispersal routes to high latitudes were available to therapsids and other tetrapods at least until early–late Permian times.

Ichibengops munyamadziensis: a new Eutherocephalian From Wuchiapingian Permian Zambia

A new eutherocephalian (Therapsida, Therocephalia) from the upper Permian Madumabisa Mudstone Formation (Luangwa Basin) of Zambia

Authors:

Huttenlocker et al

Abstract:

A new therocephalian therapsid, Ichibengops munyamadziensis, gen. et sp. nov., is described on the basis of two partial skulls from the upper Permian (Wuchiapingian) upper Madumabisa Mudstone Formation of the Luangwa Basin, Zambia. The specimens offer insights into the diversity of therocephalians in a poorly sampled region, preserving unique maxillary structures, dental morphology that is intermediate between basal therocephalians and eutherocephalians, and a maxillovomerine bridge forming an incipient secondary palate. A phylogenetic analysis of 135 craniodental and postcranial characters from 56 therapsid taxa (including 49 therocephalians) recovered I. munyamadziensis as the sister taxon of the Russian Chthonosaurus, with both taxa resolving near the hofmeyriid + whaitsiid + baurioid clade (either as the sister group to this clade or nested near whaitsiids). Ichibengops shares with Chthonosaurus several features, including a ventral maxillary flange in which the upper postcanines are situated (also in Lycosuchus), anteroposteriorly short suborbital vacuities with strongly scalloped anterior borders, a furrowed or ridged surface texture on the palatal surface of the palatine, and a possible maxillovomerine bridge (although this latter structure is incompletely preserved in Chthonosaurus). The new taxon, along with its proposed relationship to Chthonosaurus, adds to a list of sister-group pairs of Wuchiapingian tetrapods in southern Gondwana and Laurasia, indicating that effective, though largely unknown, dispersal routes persisted in Pangea at least through early late Permian times.

Tapinocephalid Dinocephalians From Middle Permian Zambia Show Both Lucas & Benton Wrong

Tapinocephalids (Therapsida, Dinocephalia) from the Permian Madumabisa Mudstone Formation (Lower Karoo, Mid-Zambezi Basin) of southern Zambia

Authors:

Sidor et al

Abstract:

Permian tetrapods from Zambia are best known from the Luangwa Basin, which was the subject of sporadic geological and paleontological work throughout the 20th century (Wallace, 1907; Dixey, 1937; Drysdall and Kitching, 1962, 1963; Attridge et al., 1964; Kemp, 1975, 1979; Davies, 1981; King, 1981; King and Jenkins, 1997; Lee et al., 1997). Based on its fossil content, the rocks of the upper member of the Madumabisa Mudstone Formation in the Luangwa Basin are considered Late Permian in age and contemporaneous with those of the Cistecephalus Assemblage Zone (AZ) of the Karoo Basin of South Africa (Angielczyk et al., 2014). Recent field work has demonstrated that a broadly distributed and relatively homogenous tetrapod fauna can be found wherever rocks of Cistecephalus AZ age are exposed across southern Africa (e.g., Malawi, South Africa, Tanzania, Zambia, and likely Mozambique; Sidor et al., 2013; Sidor, 2013).

Until recently, older tetrapod fossils from southern Africa were much rarer, with only South Africa and Zimbabwe recognized as yielding Middle Permian taxa (Catuneanu et al., 2005; Rubidge, 2005). The Karoo Basin has produced the most diverse fauna with the Eodicynodon and Tapinocephalus AZs including dicynodonts, dinocephalians, gorgonopsians, pareiasaurs, and therocephalians (Smith et al., 2012), although new radiometric dating suggests that the base of the overlying Pristerognathus AZ should be considered Middle Permian as well (Rubidge et al., 2013). Boonstra (1946) described the first dinocephalians from Zimbabwe. Unfortunately, this material now appears to be lost (Van den Heever and Grine, 1981; King, 1988). More recently, Lepper et al. (2000) described newly recovered material from the upper part of the Madumabisa Mudstone Formation of Zimbabwe and recognized both anteosaurid as well as tapinocephalian occurrences. The most recent discovery of Middle Permian tetrapods was reported by Simon et al. (2010), who noted the presence of isolated tapinocephalid remains from the middle portion of the Ruhuhu Formation of southern Tanzania. Endothiodont dicynodonts and temnospondyl amphibian remains from the same locality are currently under study by our research group.

Between 1951 and 1953, geologists from the Geological Survey Department of Northern Rhodesia were assigned to map coal reserves in the Mid-Zambezi Valley. Vertebrate fossils discovered in the course of their work were sent to S. H. Haughton for identification, and were subsequently published by Gair (1959:36) as “Dinocephalian and typical of the Tapinocephalus zone, possibly even Tapinocephalus itself.” Later, Drysdall and Kitching (1963:38) suggested that the fossils were fragmentary and unidentifiable. Unfortunately, none of the fossils was formally described and the collection now appears to be lost.

In 2010, members of our team relocated Gair's fossil site, and in July 2011 and June 2012 we collected additional tetrapod fossils there (Fig. 1; Table 1). Among them are numerous teeth that can be unambiguously referred to the tapinocephalid Dinocephalia (Boonstra, 1962; King, 1988). The discovery of this novel tetrapod assemblage provides useful biostratigraphic data for this portion of the Madumabisa Mudstone Formation in the Mid-Zambezi Basin.

A New Silesaurid Dinosauriform From Anisian Triassic Zambia

A new silesaurid from the upper Ntawere Formation of Zambia (Middle Triassic) demonstrates the rapid diversification of Silesauridae (Avemetatarsalia, Dinosauriformes)

Authors:

1. Brandon R. Peecook (a)
2. Christian A. Sidor (a)
3. Sterling J. Nesbitt (a)
4. Roger M. H. Smith (b)
5. J. Sebastien Steyer (c)
6. Kenneth D. Angielczykd

Affiliations:

(can't see them...for some reason I have lost access to JVP)

Abstract:

Recent discoveries have shown that non-dinosaurian dinosauromorphs were morphologically diverse, globally distributed, and have a stratigraphic range extending into the Upper Triassic. Silesauridae, the sister group to Dinosauria, contains at least seven species. Here we describe Lutungutali sitwensis, gen. et sp. nov., the first silesaurid from the upper portion of the Ntawere Formation of the Luangwa Basin, Zambia. The upper Ntawere Formation has been correlated with subzone C of the Cynognathus Assemblage Zone of the Karoo Basin in South Africa and the Lifua Member of the Manda beds in the Ruhuhu Basin in Tanzania, both of which are considered Anisian in age and the latter has yielded the silesaurid Asilisaurus kongwe. The results of our phylogenetic analysis, including a new pelvic character, allies Lutungutali with Upper Triassic silesaurids such as Silesaurus, Sacisaurus, and Eucoelophysis rather than with the possibly coeval Asilisaurus. The Zambian silesaurid shares a laterally oriented brevis fossa on the ilium and a transversely thin ischium in cross-section with Upper Triassic forms. Silesaurids were more diverse during their early evolution in the Anisian than previously suspected. Lutungutali and Asilisaurus are the two oldest known members of the bird-line archosaurs represented by body fossils. Together they show that a subclade of bird-line archosaurs was diversifying soon after its origin, building further support for the rapid diversification of Archosauria in the wake of the Permo-Triassic extinction.

Didn't someone raise the idea silesaurids were actually basal orinthschians? Did that not pan out?