page_title: Eichstaettisaurus
section_title: Paleobiology
hierarchical_section_title: Eichstaettisaurus / Paleobiology
caption_attribution_description: English: Gekko gecko Deutsch: Tokeh, Gekko gecko
context_page_description: Eichstaettisaurus is a genus of lizards from the Late Jurassic and Early Cretaceous of Germany, Spain, and Italy. With a flattened head, forward-oriented and partially symmetrical feet, and tall claws, Eichstaettisaurus bore many adaptations to a climbing lifestyle approaching those of geckoes. The type species, E. schroederi, is among the oldest and most complete members of the Squamata, being known by one specimen originating from the Tithonian-aged Solnhofen Limestone of Germany. A second species, E. gouldi, was described from another skeleton found in the Matese Mountains of Italy. Despite being very similar to E. schroederi, it lived much later, during the Albian stage. Fossils of both species show exceptional preservation due to deposition in low-oxygen marine environments.
  Initially named as a species of the genus Ardeosaurus by Ferdinand Broili in 1938, E. schroederi has had a convoluted taxonomic history. It was initially recognized as a relative of night lizards until research in the 1960s identified it and Ardeosaurus as geckoes. However, phylogenetic analyses conducted in the 1990s suggested that it was closer to the ancestor of all squamates.
context_section_description: Modern geckoes are unusual among lizards in that the digits of their limbs are relatively symmetrical in length, and are splayed in a broad arc; by contrast, the digits in other lizards are usually nearly parallel to each other, especially on the feet. The pattern seen in geckoes facilitates gripping while the body is in various orientations, since it spreads out the adhesive setae (bristles) on their toepads while allowing the first and last digits to oppose each other. Eichstaettisaurus schroederi exhibited two characteristics that contributed to foot symmetry: its first metatarsal was long relative to its third metatarsal (with the third metatarsal only being 1.41 times as long as the first, as opposed to 2 times in a typical lizard), and its fourth metatarsal was relatively short. In 2017, Simões and colleagues observed that E. schroederi had stronger foot symmetry than Ardeosaurus digitatellus, and they inferred that the feet of both were likely directed further forwards than other lizards. This was also supported by the lack of bicondylar articulations in the phalanges, which are an adaptation for outwards-facing feet that resists displacement in the horizontal plane while enabling flexion in the vertical plane.
  Simões and colleagues also identified several other characteristics in E. schroederi, which suggest that the scansorial (climbing-based) lifestyles of modern geckoes arose earlier than previously appreciated. Its tall claws and elongate second-from-tip phalanges on the digits are both traits that have been strongly correlated with scansorial lifestyles in lizards. In particular, the tall claws may have provided longer lever arms for the flexor tendons that retracts them, thus improving their gripping strength. Meanwhile, its relatively short limbs and flattened body may have improved climbing performance by lowering its centre of gravity, as has been suggested for the Tokay gecko, but this feature may not be correlated with scansorial lifestyles. Finally, its limbs of similar lengths may have improved grip as in the sharp-snouted rock lizard; the significance of this trait may be diminished given the adhesive toepads of geckoes, and the lack of correlation between limb length ratio and scansoriality in the Lacertidae.
  In 2004, Evans and colleagues had also discussed the lifestyle of E. gouldi in light of its bodily proportions. They pointed to a previous study on how variation between proportions among species of snow skinks (Carinascincus) was correlated with habitat usage: short torsos and long hindlimbs were correlated with rock climbing (in large species) and tree climbing (in small species), while long torsos and shorter hindlimbs were correlated with ground dwelling. Evans and colleagues found that E. gouldi was closest to the ground-dwelling species, which have slow running speeds and are relatively poor climbers, in its proportions. Nevertheless, they recognized that the flat bodies and tall claws of E. gouldi were adapted for clinging to rough surfaces. They proposed a hybrid lifestyle for E. gouldi: a slow-moving ground lizard with some capacity for climbing on rocks and hiding in crevices from predators like rhynchocephalians.
caption: The bodyplan of Eichstaettisaurus has been compared to the Tokay gecko
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