Canada to America: DIE, DIMETRODON! DIE!

Re-evaluation of the historic Canadian fossil Bathygnathus borealis from the Early Permian of Prince Edward Island

Authors:

Brink et al

Abstract:

The holotype and only known specimen of Bathygnathus borealis is a partial snout with maxillary dentition of a presumed sphenacodontid from the Lower Permian (Artinskian 283–290 Ma) redbeds of Prince Edward Island, Canada. Due to its incomplete nature, assessment of the taxon’s systematic position within a cladistic analysis had never been performed. However, recent recognition of the phylogenetic utility of tooth characters in sphenacodontids now allows for a modern phylogenetic evaluation of B. borealis. Results show that B. borealis is the sister taxon of Dimetrodon grandis, which is supported by dental characters: crowns with mesial and distal denticles and roots elongate, lacking plicidentine. An autapomorphy of B. borealis is the large facial exposure of the septomaxilla. As Bathygnathus has priority over Dimetrodon in the scientific literature, we suggest a reversal of precedence is required to preserve the familiar name Dimetrodon and to maintain universality, thus recognizing the new species Dimetrodon borealis.

Actually, its an attempt to 'save' the name.  I was being a turkey.  They recommend keeping the name 'Dimetrodon' because under the rules of naming fossils, the earliest name has priority.  The Canadian specimen was named earlier than the ones Cope named.  Therefore, by the rules the genus Dimetrodon ought to become Bathygnathus.  Dimetrodon is one of those iconic names though and why they are trying to save it.  However, that didn't work for Brontosaurus (sorta) and Seismosaurus, so its unlikely to do so here.

The Composition and Layout of a Wolfcampian/Lower Permian Woodland

Plant architecture and spatial structure of an early Permian woodland buried by flood waters, Sangre de Cristo Formation, New Mexico

Authors:

Rinehart et al

Abstract:

Natural molds of 165 stems were found in life position in a 1 m-thick sandstone bed, lower Permian (Wolfcampian), Sangre de Cristo Formation, northern New Mexico. The sandstone represents a single flood event of a river sourced in the Ancestral Rocky Mountains. Most of the flood-buried plants survived and resumed growth. The stem affinities are uncertain, but they resemble coniferophytic gymnosperms, possibly dicranophylls. Stem diameters (N = 135) vary from 1 to 21 cm, with three strongly overlapping size classes. Modern forest studies predict a monotonically decreasing number (inverse square law) of individuals per size class as diameter increases. This is not seen for fossil stems ≤ 6 cm diameter, reflecting biases against preservation, exposure, and observation of smaller individuals. Stems ≥ 6 cm diameter obey the predicted inverse square law of diameter distribution. Height estimates calculated from diameter-to-height relationships of modern gymnosperms yielded heights varying from ~ 0.9 m to greater than 8 m, mean of ~ 3 m. Mean stand density is approximately 2 stems/m2 (20,000 stems/hectare) for all stems greater than 1 cm diameter. For stems greatre than than 7.5 cm or greater than 10 cm diameter, density is approximately 0.24 stems/m2 (2400 stems/hectare) and 0.14 stems/m2 (1400 stems/hectare). Stem spatial distribution is random (Poisson). Mean all-stem nearest-neighbor distance (NND) averages 36 cm. Mean NND between stems greater than 7.5 cm and greater than than 10 cm diameter is approximately 1.02 m and 1.36 m. NND increases in approximate isometry with stem diameter, indicating conformation to the same spatial packing rules found in extant forests and other fossil forests of varying ages. Nearest-neighbor distance distribution passes statistical testing for normality, but with positive skew, as often seen in extant NND distributions. The size-frequency distribution of the stems is similar to those of Jurassic, early Tertiary, and extant woodlands; the early Permian woodland distribution line has the same slope, but differs in that the overall size range increases over time (Cope's rule). The early Permian woodland is self-thinning; its volume versus density relationship shows a self-thinning exponent between − 1.25 and − 1.5, within the range seen in some extant plant stands (− 1.21 to − 1.7).

Artinskian Permian Tetrapod Footprints From Spain

Permian Tetrapod Footprints From The Spanish Pyrenees

Authors:

Voigt et al

Abstract:

Paleozoic tetrapod footprints are a common and well-known phenomenon in almost all large European countries except for Spain. Here we report on hitherto unpublished vertebrate tracks from Permian red-beds of the south-central Pyrenees that with regard to their relative abundance, diversity and quality of preservation are suitable to fill this gap of knowledge. The described tracks come from two localities in muddy to fine-grained, sandy, alluvial plain deposits in the lower third of the Peranera Formation of the Erill-Castell Basin near Les Iglésies, northern Catalonia. The tracks can be assigned to five ichnogenera, i.e., Batrachichnus Woodworth, 1900, Limnopus Marsh, 1894, Varanopus Moodie, 1929, Hyloidichnus Gilmore, 1927, and Dromopus Marsh, 1894, that we interpret as footprints of temnospondyls, captorhinomorphs, and araeoscelids or similarly sized sauropsids with a lacertoid foot pattern. This ichnofossil assemblage is most similar to ichnofaunas from the Hermit Formation of the Grand Canyon, Arizona, the upper Abo and Robledo Mountains formations of New Mexico, and the main trace fossil site of the Tiddas Basin, Morocco, suggesting a late Early Permian (Artinskian) age for this stratigraphic level of the Peranera Formation. Considering the relative abundance and diversity of captorhinomorph footprints, the new Spanish tracefossil localities may cover the onset of the Early Permian radiation of non-diapsid eureptiles. The thick Late Paleozoic red-bed successions of the south-central Pyrenees have the potential to also bear footprints of otherwise unknown early therapsids, so systematic fossil prospecting of this area is strongly recommended.

Postglacial Sakmarian–Artinskian Permian Oceanic Paleoenvironment in Australasia

Postglacial Early Permian (late Sakmarian– early Artinskian) shallow-marine carbonate deposition along a 2000 km transect from Timor to west Australia

Authors:

Haig et al

Abstract:

Late Sakmarian to early Artinskian (Early Permian) carbonate deposition was widespread in the marine intracratonic rift basins that extended into the interior of Eastern Gondwana from Timor in the north to the northern Perth Basin in the south. These basins spanned about 20° of paleolatitude (approximately 35°S to 55°S). This study describes the type section of the Maubisse Limestone in Timor-Leste, and compares this unit with carbonate sections in the Canning Basin (Nura Nura Member of the Poole Sandstone), the Southern Carnarvon Basin (Callytharra Formation) and the northern Perth Basin (Fossil Cliff Member of the Holmwood Shale). The carbonate units have no glacial influence and formed part of a major depositional cycle that, in the southern basins, overlies glacially influenced strata and lies a short distance below mudstone containing marine fossils and scattered dropstones (perhaps indicative of sea ice). In the south marine conditions became more restricted and were replaced by coal measures at the top of the depositional sequence. In the north, the carbonate deposits are possibly bryozoan–crinoidal mounds; whereas in the southern basins they form thin laterally continuous relatively thin beds, deposited on a very low-gradient seafloor, at the tops of shale–limestone parasequences that thicken upward in parasequence sets. All marine deposition within the sequence took place under very shallow (inner neritic) conditions, and the limestones have similar grain composition. Bryozoan and crinoidal debris dominate the grain assemblages and brachiopod shell fragments, foraminifera and ostracod valves are usually common. Tubiphytes ranged as far south as the Southern Carnarvon Basin, albeit rarely, but is more common to the north. Gastropod and bivalve shell debris, echinoid spines, solitary rugose corals and trilobite carapace elements are rare. The uniformity of the grain assemblage and the lack of tropical elements such as larger fusulinid foraminifera, colonial corals or dasycladacean algae indicate temperate marine conditions with only a small increase in temperature to the north.

The depositional cycle containing the studied carbonate deposits represents a warmer phase than the preceding glacially influenced Asselian to early Sakmarian interval and the subsequent cool phase of the "mid" Artinskian that is followed by significant warming during the late Artinskian–early Kungurian. The timing of cooler and warmer intervals in the west Australian basins seems out-of-phase with the eastern Australian succession, but this may be a problem of chronostratigraphic miscorrelation due to endemic faunas and palynofloras.

How Many Dimetrodon Species Are Present in the Artinskian Permian Briar Creek Bonebed

Long bone histology indicates sympatric species of Dimetrodon (Lower Permian, Sphenacodontidae)

Authors:

Christen D. Shelton, P. Martin Sander, Koen Stein and Herman Winkelhorst

Abstract:

The Briar Creek Bonebed (Artinskian, Nocona Formation) in Archer County is one of the richest sources of Dimetrodon bones in the Lower Permian of Texas, USA. Based on size, a small (D. natalis), an intermediate (D. booneorum), and a large species (D. limbatus) have been described from this locality. It has been proposed that these traditionally recognised species represent an ontogenetic series of only one species. However, the ontogenetic series hypothesis is inconsistent with the late ontogenetic state of the small bones, as suggested by their osteology and degree of ossification. Histological analysis of newly excavated material from the Briar Creek Bonebed has resolved some of the discretion between these two competing hypothesis, confirming the coexistence of a small (D. natalis) with at least one larger Dimetrodon species. An external fundamental system is present in the largest sampled long bones identified as D. natalis. The histology of D. natalis postcrania is described as incipient fibro lamellar bone. This tissue is a combination of parallel-fibred and woven-fibred bone that is highly vascularised by incipient primary osteons. The species status of D. booneorum and D. limbatus remain unresolved.

Were Paleozoic Cycads Preadapted to Growing in Groves?

The ancient cycad lineage has been around since before the age of the dinosaurs. More recently, cycads also co-existed with large herbivorous mammals, such as the ice age megafauna that only went extinct a few tens of thousands of years ago. Cycads that are living today have large, heavy seeds with a fleshy outer coating that suggests they rely on large bodied fruit-eating animals to disperse their seeds. Yet there is little evidence that they are eaten and dispersed by today's larger-bodied animals, such as emus or elephants. If these plants are adapted for dispersal by a set of animals that has been missing from Earth's fauna for tens of thousands of years, then how can they still be around today? A new study proposes that the clumped dispersal mechanism these ancient plants most likely relied upon still serves them well today.

Fossil cycads are recorded from 280 million years ago around the time coniferous forests first arose. The ecological distribution pattern of many living cycads today suggests they have limited and ineffectual seed dispersal. For example, Macrozamia miquelii, a cycad endemic to Australia, is found in highly clumped, dense, numbers, where it dominates the understory. Moreover, large areas of seemingly suitable habitat often separate populations from each other. These patterns suggest that few to none of the seeds are being dispersed large distances away from parent plants, one of the long-standing tenets of the advantages of seed dispersal.

Fires During the Permian

The burning of Gondwana: Permian fires on the southern continent—A palaeobotanical approach

Authors:

1. André Jasper (a)
2. Margot Guerra-Sommer (b)
3. Abdalla M.B. Abu Hamad (c)
4. Marion Bamford (d)
5. Mary Elizabeth Cerruti Bernardes-de-Oliveira (e, f)
6. Rajni Tewari (g)
7. Dieter Uhl (h, i)

Affiliations:

a. Centro Universitário UNIVATES, Lajeado, Brazil

b. Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil

c. The University of Jordan, Amman, Jordan

d. BPI Palaeontology, University of the Witwatersrand, Johannesburg, South Africa

e. Universidade de Guarulhos, Guarulhos, Brazil

f. Universidade de São Paulo, São Paulo, Brazil

g. Birbal Sahni Institute of Palaeobotany, Lucknow, India

h. Senckenberg Forschungsinstitut und Naturmuseum Frankfurt, Frankfurt am Main, Germany

i. Senckenberg Centre for Human Evolution and Palaeoenvironment, Eberhard Karls Universität Tübingen, Tübingen, Germany

Abstract:

Fossil charcoal has widely been accepted as a direct indicator for the occurrence of palaeo-wildfires. In Upper Palaeozoic sediments of Euramerica and Cathaysia, records of these remains are relatively common and (regionally and stratigraphically) more or less homogeneously distributed in terrestrial sequences. On the other hand, just a few records have been published for the Permian of Gondwana and only recently has it been demonstrated that macroscopic charcoals are also common here. Most Permian macroscopic charcoal from Gondwana is gymnospermous and has been reported from coal-bearing strata. Macroscopic charcoal occurrences are spread out in different sequences and also in distinct stratigraphic intervals in the Permian [e.g., Paraná Basin (Sakmarian/Artinskian of Brazil), Karoo Basin (Artinskian of South Africa), Damodar Basin (Lopingian of India) and Dead Sea area (Changhsingian of Jordan)]. They range from peri-glacial/post-glacial to warm temperate climatic systems throughout the Permian. Macro- and micro-charcoal occurrences are compared to inertinite incidences to support the pyrogenic origin for these coal macerals and to provide an up to date overview on the known evidences of Permian wildfires on Gondwana in space and time.

This has some serious implications for the paleoatmosphere:  you don't get fires if the oxygen level falls too low.  This goes from the Sakmarian to the Lopingian.