The Complicated Teeth of Sphenacodonts

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.

Appears Dimetrodon Relative Ophiacodon was Warm Blooded

Most people know that ‘warm-bloodedness’ is a characteristic of mammals. This trait actually encompasses a suite of physiological processes that help to maintain a relatively high, constant body temperature using heat generated internally. A new study by Christen Don Shelton of the University of Cape Town, South Africa and his colleague, Martin Sander at the University of Bonn, Germany, presented at this year’s Society of Vertebrate Paleontology meeting, shows that this character may have shown up in the ancestors of modern mammals far earlier than was previously thought.

One associated effect of being ‘warm-blooded’ is a relatively fast growth-rate. Mammals (and birds, who are also ‘warm-blooded’) tend to grow much faster than ‘cold-blooded’ vertebrates, like fish and reptiles. This fast growth rate is in turn associated with a particular type of bone growth pattern, called fibrolamellar bone (FLB). Both mammals and birds have FLB, and Shelton and his colleague investigated its presence in an early fossil relative of mammals, Ophiacodon.

Ophiacodon is distantly related to the large sail-back reptile, Dimetrodon, that people may be familiar with, and lived in North America around 280-300 million years ago. Although it didn’t look particularly mammal-like (you could be forgiven for calling it a ‘lizard’), it has many characters that link it with mammals. The highly vascularized tissue had previously been observed in Ophiacodon, but its presence had been written off to ecological factors, like its aquatic lifestyle, rather than to its fundamental physiology. Shelton looked at a number of bones of Ophiacodon of individuals of different ages, and found that the more likely explanation is that Ophiacodon was at least partly ‘warm-blooded’

link.

Changes in Permian Pecylosaur Composition of Permian Terrestrial European Ecologies

Patterns of changes in Theromorph taxa of Permian terrestrial communities of Eastern Europe

Author:

Ivakhnenko

Abstract:

The evolution of Late Permian tetrapod communities which include Theromorpha is examined in the territory of Eastern Europe. It is noteworthy that changes in the taxonomic composition of analogous ecobiomorph groups are connected with certain biotic or abiotic factors. The analysis of these factors allows the recognition of presumable causes of the crises in communities, which are determined to a greater or lesser extent by taxonomic changes. It is shown that the crisis in the middle of the Permian was caused primarily by abiotic (tectonic) reasons, while the crisis at the end of the Permian was complex, determined by a combination of biotic, local tectonic, and global factors.

Pelycosaur Pantelosaurus Bonebed From Permian Germany

From about 1.2 meters long , internationally unique fossil record of Pantelosaurus ( Haptodus ) Saxonicus ( Saxon Pelycosaurier the Permian period ) were obtained on May 6, 2014, a special drill two fossil bone samples to investigate this in more detail . The scientists hope the basis of the bone thin sections of the samples in the microscope to detect cell pattern in order to meet , among others, statements regarding the growth of animals.

The Saxon - Pelycosaurier finds come from the Doehlen pool near Freital and were discovered in the early 20th century when mining as Beifund . Frederik Spindler, a paleontologist at the University of Freiberg , Dr. Johannes Richter , Head of Unit for geoarchives , geoinformation , Collections State Agency for Environment , Agriculture and Geology, and Christians Shelton of the University of Bonn withdrawals , the samples in Freiberg.

The tests run as part of a three-year DFG research project on "Revision of the early Sphenacodontier " . The joint project is running since May 2012 under the direction of Prof. Jörg W. Schneider (TU Freiberg ) and Professor Martin Sander of the Steinmann Institute in Bonn . In the summer of 2013, the researchers have made similar investigations on alleged pups this dinosaur .

translated from here.

Pelycosaurian-grade Synapsids Have a Very Incomplete Fossil Record

Current and historical perspectives on the completeness of the fossil record of pelycosaurian-grade synapsids

Authors:

Brocklehurst et al

Abstract:

Understanding of the early evolution of tetrapods may have been influenced by the effects of geological and anthropogenic sampling biases, as suggested by previous studies. Here we make a thorough assessment of how these and other biases affect the record of pelycosaurian-grade synapsids, a group of tetrapods that dominated the terrestrial realm during the late Carboniferous and early Permian. Modified versions of the character and skeletal completeness metrics are used to assess the completeness of the known specimens, while a recently published supertree of basal synapsids is tested for congruence between the stratigraphic and phylogenetic hypotheses. A historical analysis is also applied to the record in order to show how the biases in the study of this group over the past centuries may have influenced the current record. The results show that the completeness of basal synapsid specimens shows very little variation throughout the Early Permian. A peak in skeletal and character completeness metric values in the Middle Permian (Wordian) is attributed to exceptional preservation of the Mezen fauna. A significant negative correlation is found between the skeletal completeness metric and a taxic diversity curve of pelycosaurs, implying a tendency to name many species based on poor material. The lack of correlation between the character completeness metric and diversity is attributed to the history of discovery in the group: the majority of pelycosaur species were named between the 1930s and 1960s, when character based assignments were secondary to size, location and stratigraphy. A strong correspondence between the phylogeny and stratigraphy implies a reliable phylogenetic hypothesis, but the low relative completeness index score suggests that a great deal of the fossil record is missing. While the relative completeness index has improved over the past century, the rate of improvement has slowed in the last two decades, and the slowing rate of discovery of new species suggests that the limit of what the fossil record of pelycosaurs has to offer is being approached. A consistent shape of diversity curves over the past century implies that the same biases which affected the record in the past are still affecting it now. This study highlights the need for sampling correction methods to be employed in studies of early synapsids.

Dimetrodon Demonstrated to be Eating Lepospondyl Diplocaulus in Middle Permian Texas

Talk about a creature feature: A bizarre boomerang-headed amphibian that burrowed in a seasonal pond in what is now Texas often met its doom in the jaws of a reptilian fin-backed mammalian ancestor, new fossils reveal.

These two weird critters were residents of the Permian period 298 million to 250 million years ago, before dinosaurs roamed the Earth. Dimetrodon, the jaguar-size finback, looked like a lizard but was actually more closely related to modern mammals. Diplocaulus, the boomerang-head, was a truly strange amphibian with an impractically wide, bony skull.

[...]

Bakker and his colleagues discovered the Dimetrodon and Diplocaulus interaction in the Craddock bone bed in Baylor County, Texas. The bone bed is scattered with the bodies of boomerang-heads, curled in what were once burrows. The amphibians seem to have burrowed into the mud to survive the dry season, the researchers reported here Monday at the annual meeting of the Geological Society of America.

"The bed had a reputation of just being a stew pot with everything mixed together," Bakker said. "That's totally wrong. It's beautifully layered."

The excavations revealed that boomerang-heads were common in the pond — and that something was snacking on them.

"We have hundreds of these, mostly chewed, and even the guys in burrows got attacked," Bakker said.

The shed teeth, "like bullets in a crime scene," revealed the attacker to be Dimetrodon, he said. The finback's sharp fangs and long snout would have enabled it to bite boomerang-heads hiding in burrows, perhaps after partially excavating them with its sharp, digging claws.

One cluster of eight juvenile boomerang-heads was found stacked together, suggesting they all occupied the same burrow. Dimetrodon likely killed the top three, including one whose nose was bitten clean off (taking part of the brain with it). The other five boomerang-heads survived the Dimetrodon, only to perish during the next dry season, Bakker said.

link.

Evolution and Extinction of the Synapsids From the Carboniferous Through the Permian

The early evolution of synapsids, and the influence of sampling on their fossil record

Authors:

1. Neil Brocklehurst (a)
2. Christian F. Kammerer (a)
3. Jörg Fröbisch (a)

Affiliation:

a. Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstrae 43, D-10115 Berlin, Germany.

Abstract:

Synapsids dominated the terrestrial realm between the late Pennsylvanian and the Triassic. Their early evolution includes some of the first amniotes to evolve large size, herbivory, and macro-predators. However, little research has focused on the changes in diversity occurring during this early phase in their evolutionary history, with more effort concentrating on later events such the Permo-Triassic extinction. Here we assess synapsid diversity, at both the species and genus levels, between the Carboniferous (Moscovian) and the Middle Permian (Capitanian). A raw, taxic diversity (richness) estimate is generated, and we use two separate methods to correct for sampling biases in this curve. To remove the effect of anthropogenic sampling bias, we apply a recently published modification of the residual diversity method, and then generate a supertree, using matrix representation with parsimony to infer ghost lineages and obtain a phylogenetic diversity estimate. The general diversity pattern reflects the initial diversification of synapsids in the late Pennsylvanian and early Cisuralian, which was followed by an extinction event during the Sakmarian. Diversity recovered during the Artinskian and Kungurian, coinciding with the radiation of Caseidae, although other families begin to decline. A second extinction event occurred across the Kungurian/Roadian boundary, in which Edaphosauridae and Ophiacodontidae died out although Caseidae and Therapsida diversified. The sampling-corrected curves reveal further extinction during the Roadian, although therapsids were again unaffected. Pelycosaurian-grade synapsids survived during the Wordian and Capitanian, but were a minor part of an otherwise therapsid-dominated fauna. Evidence of significant anthropogenic sampling bias calls into question previous diversity studies that have not employed sampling correction.

Pelycosaur Found in Nova Scotia (either Sphenacodont or Edaphosaurid)

(partially intact rib cage)

A Nova Scotia family out for a walk with their dog has stumbled upon what the province is calling its most significant fossil find.

Patrick Keating and his wife Susie were walking their dog Kitty last month along the Northumberland Shore when something caught their eye.

“(It) looked like a chicken breast, you know, encapsulated in rock. But it was interesting once we found out what it was,” said Susie Keating.

It turned out to be the partial sail, ribcage and backbone of the sail-back reptile, the first to be found in Nova Scotia, the provincial government said in a press release.

"This is a great day for Nova Scotians and the world," Minister of Communities, Culture and Heritage Leonard Preyra said in a statement.

A week later, while walking along the same stretch of beach, the family found the animal’s skull, believed to be 290 million to 305 million years old.

Patrick's brother brought the fossil to the Nova Scotia Museum, which promptly gave it a nickname -- Superstar

“When I finally saw a picture all I could think of was, ‘Oh my God, oh my God,’ because this is part of the missing piece of the puzzle that we're putting together based on the fossils we're finding here in Nova Scotia,” said Ken Adams, Director of Fundy Geological Museum.

Palaeontologists knew the sail-back, a mammal-like reptile, once roamed these parts because in 1994 footprints were found in Nova Scotia's Colchester County, and isolated bones were discovered in 1845 in Prince Edward Island.

Sail-back reptiles have been found in Texas and Europe, which were attached to Nova Scotia more than more than 300 million years ago before the tectonic plates beneath them shifted.

Link (video on the other side of link). 

Is this actually a Dimetrodon?  The video clip shows the museum display with a diagram that highlights the portions found on a dimetrodon skeleton.  So, yes?  No?