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| Sphenodraco scandentis Beccari, Guillaume, Jones, Villa, Cooper Regnault & Rauhut, 2025 artwork by Gabriel Ugueto facebook.com/serpenillus |
Abstract
Here, we describe a new species of Jurassic rhynchocephalian from the Solnhofen Archipelago, Sphenodraco scandentis gen. et sp. nov., and highlight the importance of the postcranial anatomy for ecomorphological studies in the rhynchocephalian clade. The holotype of Sphenodraco scandentis is divided into a main slab, which has been mentioned in the literature and previously assigned to Homoeosaurus maximiliani, and a counterslab containing most of its skeletal remains. This new taxon shows an exclusive combination of osteological features that differs from previously described rhynchocephalians. Sphenodraco was recovered in our phylogenetic analysis as a component of a clade including Homoeosaurus and Kallimodon. To evaluate the ecomorphology of the new taxon, we compare fossil rhynchocephalians with the extant tuatara and squamates. We quantify the diversity of body proportions in lepidosaurs systematically, inferring lifestyle for extinct rhynchocephalians. Our analysis suggests that fossil rhynchocephalians had a diverse array of substrate uses, with some categorized as good climbers, and with Sphenodraco showing the extreme condition of limb elongation found in strictly arboreal lizards. This new taxon is here regarded as the first predominantly or even strictly arboreal rhynchocephalian. Furthermore, our analysis shows that the diversity of fossil rhynchocephalians might still be underestimated.
ecomorphology, Germany, Jurassic, Rhynchocephalia, sphenodontian, taxonomy, tuatara
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| Photograph of the holotype of Sphenodraco scandentis. A, SMF R414, the main slab, containing some bone remains and the imprint of the skeleton. B, NHMUK PV R 2741, the counterslab, containing most of the skeletal remains |
Lepidosauria Haeckel, 1866,
Rhynchocephalia Günther, 1867,sensuDeMar et al. (2022),
Neosphenodontia Herrera-Flores et al., 2018
Sphenodraco gen. nov.
Derivation of name: The genus name combines the prefix spheno- (which composes the name Sphenodontia) and draco (Latin for ‘dragon’, but also in reference to the arboreal gliding lizards, whose limb proportions are similar to that of the new taxon) and translates to ‘the sphenodontian dragon’. The genus name is masculine.
Type species: Sphenodraco scandentis gen. et sp. nov., by monotypy.
Sphenodraco scandentis sp. nov.
Derivation of name: The species name comes from the Latin word scandens, meaning ‘climber’.
Diagnosis: Small rhynchocephalian with the following unique combination of traits: (i) maxillary dentition with posterior flanges decreasing in size posteriorly among the last three teeth; (ii) bases of the maxillary teeth are oblique to the tooth row (in labial view)*; (iii) short posterior process of the pleurapophysis of sacral vertebra 2; (iv) tall, funnel-shaped proximal epiphysis of the humerus; (v) tall acetabular region of the ilium, with posteriorly oriented iliac blade; (vi) short pubic process of the ilium*; (vii) slender stylopodia and zeugopodia, with the diameter being <.06 of the length between metaphyses; and (viii) metacarpal and metatarsal IV longer than III. An asterisk (*) represents autapomorphic features.
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| Living reconstruction of Sphenodraco scandentis in the Solnhofen Archipelago in Germany during the late Jurassic period. artwork by Gabriel Ugueto |
Victor Beccari, Alexandre R. D. Guillaume, Marc E. H. Jones, Andrea Villa, Natalie Cooper, Sophie Regnault and Oliver W. M. Rauhut. 2025. An arboreal rhynchocephalian from the Late Jurassic of Germany, and the importance of the appendicular skeleton for ecomorphology in lepidosaurs. Zoological Journal of the Linnean Society. 204(3); zlaf073, DOI: doi.org/10.1093/zoolinnean/zlaf073 [02 July 2025]