Stenokranio boldi
- 演化之聲
- Mar 19
- 3 min read
Updated: 1 day ago
Age
Carboniferous（Gzhelian）-Permian（Asselian）
303-293 Ma
Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Temnospondyli
Family: Eryopidae
Genus: Stenokranio
Species: Stenokranio boldi
Morphological description
Stenokranio boldi is a large amphibian that lived from the late Carboniferous to the early Permian and belongs to the family Eryopidae. Known material includes two well-preserved skulls and partial postcranial remains. The skull lengths are 24.7 cm in the holotype (NHMMZ/LS PW 2019/5025) and 27 cm in the paratype (NHMMZ/LS PW 2019/5022). The skull is longer than wide, with a broad, arcuate outline in dorsal view, a bluntly rounded snout, and a short postorbital region. The posterior skull width is relatively small (pSw/Sl = 0.92), and the lateral margins are nearly straight and parallel.
The postparietals and tabulars form a short longitudinal bony strip. The dorsal skull surface bears a coarse, reticulated sculpture composed of numerous pits and ridges. Paired longitudinal ridges extend from the temporal region to the preorbital area, accompanied by additional transverse ridges.
Cranial features include radially arranged ridges on the nasals; equal internarial and interorbital widths; a small distance between the supratemporals (Hw/Sl approximately 0.42–0.43); and an occipital margin that is nearly straight or slightly concave. The palatine is broad and articulates with a wide ectopterygoid, whose posterior portion is equal in width to the pterygoid. The ectopterygoid, palatine, and vomer each bear a pair of fangs; those on the palatine are the largest, whereas those on the vomer and ectopterygoid are similar in size and consist of two teeth each. The choana is short and nearly circular. The skull base is broad, short, and smooth, lacking denticles.
The mandible possesses approximately 48–50 marginal tooth positions. The dentition is homodont and relatively small, decreasing in size from anterior to posterior, with no distinct canine region. Tooth crowns are arranged in a straight line, and the apices are slightly curved lingually. The surangular process is relatively low.
Postcranial remains are limited and include the atlas arch, several vertebrae and ribs, and elements of the pectoral girdle. Neural spines are roughened. Some ribs possess uncinate processes, whereas others do not. The clavicle is narrow, and the cleithrum is longer than the clavicle. The interclavicle is slightly wider than long (Icll/Iclw = 0.82–0.90) and bears a pectinate anterior margin. The scapulocoracoid is tall, and the angle between the scapular blade and the supraglenoid buttress is approximately 90° or slightly greater. The supraglenoid buttress is elongated in the anteroposterior direction.
Etymology
The genus name Stenokranio derives from the Greek stenos (narrow) and kranio (skull), referring to the relatively narrow posterior skull.
The species name boldi honors Rudolf Bold of Rammelsbach near Kusel, Germany, who discovered the holotype of Cryptovenator hirschbergeri in the Remigiusberg Formation in 2002.
Biological description
Stenokranio boldi lived during the Gzhelian to Asselian stages of the late Carboniferous to early Permian, approximately 303–293 million years ago, in the Saar–Nahe Basin of southwestern Germany. It inhabited fluvio-lacustrine environments, indicating a semiaquatic lifestyle .
This species was among the largest predators in its ecosystem. It likely hunted by ambush or active searching and was capable of moving effectively both in water and along shorelines. It probably foraged along riverbanks and lake margins, feeding primarily on aquatic vertebrates.
Stenokranio boldi coexisted with sarcopterygian and actinopterygian fishes, xenacanthid sharks, dvinosaurian temnospondyls such as Dvinosaurus, and various terrestrial or semiaquatic tetrapods, including diadectomorphs and synapsids .
Phylogenetic analysis indicates that Stenokranio boldi is a relatively derived member of Eryopidae and forms a sister taxon to Eryops.
(Author: Shui-Ye You)
Reference
Werneburg R et al. (2023). A new eryopid temnospondyl from the Carboniferous-Permian boundary of Germany. Journal of Paleontology.
49.53, 7.45
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