Raw Landmarks for describe head shape in two spiny lizards from central Mexico

Description

Geometric morphometric techniques offer valuable insights into the developmental processes underlying morphological variation. This dataset includes two-dimensional coordinates (X and Y) for 22 cranial landmarks digitized on lateral images of two lizard species: Sceloporus grammicus and Sceloporus aeneus. These species differ in their reproductive mode—viviparous and oviparous, respectively. Landmark data were collected from adult males and females to test whether developmental instability, inferred from fluctuating asymmetry in head shape, exhibits sex-specific patterns within each species. Landmarks were digitized using TPSDig and subsequently visualized and analyzed in MorphoJ. The dataset is accompanied by an image file ("Landmarks.jpg") illustrating the anatomical location of each landmark. All data were collected under the scientific collecting permit SGPA/DGVS/10352/21 issued by SEMARNAT (Mexico). The resulting analyses found no evidence of sex-specific developmental instability in either species. These data can be reused for further morphometric investigations, comparative analyses across squamate taxa, or as a reference for studies in evolutionary developmental biology.

Steps to reproduce

Adult individuals of Sceloporus grammicus and Sceloporus aeneus were collected from natural populations in central Mexico under the scientific permit SGPA/DGVS/10352/21 issued by SEMARNAT. Individuals were sexed based on secondary sexual characteristics and photographed in strict dorsal view using a digital camera mounted on a fixed tripod. Each specimen was positioned with the head aligned along a horizontal axis on a flat, neutral background under consistent lighting conditions to minimize distortion and shadow. Images were then loaded into TPSDig v.2.31, where 22 homologous landmarks were manually digitized on cranial scale intersections that best represent overall head shape. These landmarks were chosen to maximize anatomical correspondence across individuals and species. No sliding semilandmarks were used. The resulting raw X and Y coordinates were exported as plain text files. Although this dataset contains unprocessed (raw) landmark data, users are encouraged to perform Procrustes superimposition, centroid size calculation, and asymmetry analysis using software such as MorphoJ, PAST v5, or the geomorph package in R. All steps were conducted following established best practices in geometric morphometrics (Zelditch et al., 2012), ensuring data consistency and reproducibility across specimens and taxa. The dataset is accompanied by an image file ("Landmarks.jpg") illustrating the anatomical location of each landmark

Institutions

• Universidad Autonoma del Estado de Mexico

  México, Toluca
• Universidad Autonoma Metropolitana Unidad Lerma

  Estado de México, Lerma

Categories

Funders

• Secretaría de Ciencia Tecnología e Innovación

  Mexico City, Mexico

Licence