Photogrammetry and Morphological Analysis of Bird Skulls
Abstract
One aspect of the study of evolutionary history is the relationship between anatomical forms and how it relates to their necessary function for survival. An example of this form and function relationship is how a wide variety of animals, such as whales, humans, and birds, all share the same skeletal structures. However, the use of these structures differs drastically. Since birds lack forelimbs and teeth, they depend on their beaks to survive. This results in a diverse range of birds’ skulls, with the ability to tear apart animal flesh or drill into trees to pick out insects. The goal of our study was to find out how diversity in skull morphology relates to ecological function by quantifying shape and size variation from 3D anatomical models produced with photogrammetry. Our study focused on the songbird superfamily Emberizoidea, whose biodiversity spans the entire Western Hemisphere and inhabits nearly all ecological niches they have evolved into. We loaned skulls representing these species from the Cincinnati Museum Center’s Zoology Collection. We photographed them hundreds of times from multiple overlapping angels using a DLSR camera and a rotating turntable. We uploaded these images into the Morpho Cloud virtual desktop platform where we analyzed them using Slicer Morph. We first masked these photos to remove the background from the foreground and to separate the skull for model building. Once all the photos from each set were complete, it was developed into a 3D model using OpenDroneMap software (ODM). We edited these models in MeshLab and resized them for downstream analysis. This research demonstrates that photogrammetry is an effective method to produce 3D models of detailed skeletal structures in the skulls of the superfamily Emberizoidea, which can be used in further research about the evolution of functional anatomy.
Photogrammetry and Morphological Analysis of Bird Skulls
One aspect of the study of evolutionary history is the relationship between anatomical forms and how it relates to their necessary function for survival. An example of this form and function relationship is how a wide variety of animals, such as whales, humans, and birds, all share the same skeletal structures. However, the use of these structures differs drastically. Since birds lack forelimbs and teeth, they depend on their beaks to survive. This results in a diverse range of birds’ skulls, with the ability to tear apart animal flesh or drill into trees to pick out insects. The goal of our study was to find out how diversity in skull morphology relates to ecological function by quantifying shape and size variation from 3D anatomical models produced with photogrammetry. Our study focused on the songbird superfamily Emberizoidea, whose biodiversity spans the entire Western Hemisphere and inhabits nearly all ecological niches they have evolved into. We loaned skulls representing these species from the Cincinnati Museum Center’s Zoology Collection. We photographed them hundreds of times from multiple overlapping angels using a DLSR camera and a rotating turntable. We uploaded these images into the Morpho Cloud virtual desktop platform where we analyzed them using Slicer Morph. We first masked these photos to remove the background from the foreground and to separate the skull for model building. Once all the photos from each set were complete, it was developed into a 3D model using OpenDroneMap software (ODM). We edited these models in MeshLab and resized them for downstream analysis. This research demonstrates that photogrammetry is an effective method to produce 3D models of detailed skeletal structures in the skulls of the superfamily Emberizoidea, which can be used in further research about the evolution of functional anatomy.
