Researchers have identified a new species of early tetrapod from the Lower Permian of Germany. It is a plant-eater, and it has been named Diadectes dreigleichenensis.  The fossils originate from the Bromacker locality in central Germany.  The ancient creatures from the Bromacker locality lived approximately 290 million years ago.  The site is helping palaeontologists to better understand the evolution of herbivory in early vertebrate ecosystems.

Fossil skull material showing the teeth in the jaws and palatal teeth rows. A new species of advanced reptiliomorph has been named (Diadectes dreigleichenensis). Picture credit: Carola Radke, Museum für Naturkunde Berlin.

Picture credit: Carola Radke, Museum für Naturkunde Berlin

Diadectes dreigleichenensis

The lower Permian Bromacker locality, situated in the UNESCO Global Geopark Thüringen Inselsberg – Drei Gleichen, central Germany, represents a unique inland fossil ecosystem that preserves a diverse early tetrapod fauna.  This palaeoenvironment is dominated by advanced reptiliomorphs, land animals that show a variety of amphibian as well as reptilian traits.  Lead author of the study, PhD student Jasper Ponstein (Museum für Naturkunde and the Humboldt-Universität zu Berlin) explained that the research team examined skull and jaw material representing the Diadectomorpha.  The research has been published in the Royal Society Open Science.

The researchers used traditional examination techniques that involved carefully measuring the bones in the skull and jaws and comparing them to specimens in other collections.  In addition, CT scans were undertaken to reveal fine details obscured by matrix.  This research supports the identification of a third species of the group, representing a second species of the genus Diadectes, from Bromacker. This adds to the already diverse fauna of this herbivore-dominated ecosystem.

Since the 1990s palaeontologists have described fossil specimens belonging to the Diadectes genus from the Bromacker site. These specimens had all been assigned to a single species – Diadectes absitus.  Diadectes is a member of the Diadectidae family.  This family of reptilomorphs show both amphibian and amniote characteristics.  They evolved during the Early Carboniferous (Mississippian subperiod), and their fossils are known from America, Asia and Europe. These animals are typically, robust, heavily-built tetrapods.  They had strong, deep jawbones and molar-like teeth adapted to a diet of plants.

Diadectes dreigleichenensis fossil jawbone shown in lateral view. The jaw is robust, and the molar-like teeth are adapted for the efficient grinding of plant material. Picture credit: Carola Radke, Museum für Naturkunde Berlin.

Picture credit: Carola Radke, Museum für Naturkunde Berlin

The Diadectomorpha include the earliest known herbivorous tetrapods, which evolved 305 million years ago in North America during the Late Carboniferous. Through the Late Carboniferous and much of the early Permian, herbivores remained a rare component of their respective ecosystem.

Abundant Early Herbivores

The Bromacker quarry is extremely significant.  It preserves evidence of the earliest ecosystem known in which herbivores were highly abundant.  Palaeontologists consider the Bromacker locality as the first modern ecosystem with a food chain that is recognisable today.  Herbivores make up the greatest proportion of vertebrates present.  In comparison, there are few secondary and apex predators.  The herbivore fossil record at this location includes numerous and exquisitely preserved skeletons of the diadectomorphs Diadectes absitus and Orobates pabsti, the pot-bellied caseid Martensius bromackerensis and the small agile lizard-like bolosaurid Eudibamus cursoris.

Jasper Ponstein outlined how the study was undertaken.  He stated:

“These skulls are preserved with the jaws firmly attached to the rest of the skull. Key features related to feeding, like the tooth row and the shape of the jaw joint, are obscured by the skull.  Through the CT-scans, we could actually reconstruct what these regions look like and compare the different specimens”.

The detailed study of the skull fossils revealed that diadectomorphs have a sinuous row of teeth on their lower jaws.  In addition, there are two rows of conical teeth located on the palate and a long blade-like process connected to the jaw joint.  The teeth in the lower jaw are widely spaced to maximise the available plant grinding surface. The blade-like process of the jaw joint probably played a role in helping to support the jaw whilst plant material was masticated. These adaptations allowed diadectomorphs to more effectively grind vegetation. Furthermore, the powerful CT images revealed a few replacement teeth within the palate. This suggests that diadectomorphs occasionally replaced their palatal teeth as well.

These observations enabled the research team to conclude that there was sufficient variation between the skulls to erect a new species – Diadectes dreigleichenensis.

Ponstein remarked:

“We named the species after UNESCO Global Geopark Thüringen Inselsberg – Drei Gleichen, which also contains the world-famous Bromacker locality. The species name is after Drei Gleichen, which means three of the same, in reference to the seemingly similar looking three diadectids from Bromacker, just like three iconic castles from the Middle Ages, each situated on a hilltop between Gotha and Erfurt within the Geopark.”

Co-author Professor Jörg Fröbisch (Humboldt-Universität zu Berlin) added:

“The ongoing Bromacker project is a prime example of an innovative and interdisciplinary research and science communication program, building on a multiple-decade-long international collaboration.”

Everything Dinosaur acknowledges the assistance of a media release from the Museum für Naturkunde, Berlin in the compilation of this article.

The scientific paper: “A comprehensive phylogeny and revised taxonomy of Diadectomorpha with a discussion on the origin of tetrapod herbivory” by Ponstein, J., MacDougall, M.J., and Fröbisch, J. 2024 published in the Royal Society Open Science.

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