Craniofacial form and function in Metriorhynchidae (Crocodylomorpha: Thalattosuchia): modelling phenotypic evolution
Mark T Young1, Mark A Bell, Stephen L Brusatte
1School of Geosciences, University of Edinburgh, Edinburgh, UK. zoologika@gmail.com
Biology Letters
|May 6, 2011
Summary
Metriorhynchid crocodylomorphs evolved diverse skull shapes for marine life. Geometric morphometrics and finite-element analysis reveal distinct evolutionary paths in geosaurines and metriorhynchines, indicating different selection pressures.
Area of Science:
- Paleontology
- Evolutionary Biology
- Biomechanics
Background:
- Metriorhynchid crocodylomorphs were unique archosaurs fully adapted to a pelagic lifestyle during the Jurassic and Early Cretaceous.
- This group exhibited significant ecological and morphological diversity, including large predators and specialized fish/squid eaters.
Purpose of the Study:
- To investigate craniofacial evolution in metriorhynchid crocodylomorphs using an integrated approach.
- To examine the relationship between skull form (geometric morphometrics) and function (finite-element analysis) in this clade.
Main Methods:
- Geometric morphometrics to quantify skull shape.
- Finite-element analysis (FEA) to assess biomechanical function and stress distribution.
- Phylogenetic analysis with maximum-likelihood methods to model evolutionary patterns.
Main Results:
- FEA stress values significantly correlated with skull length and breadth, linking form and function.
- Geosaurines showed evolutionary patterns best explained by Brownian motion for both form and function.
- Metriorhynchines exhibited stasis in form but directional change in function towards efficient piscivory.
Conclusions:
- The two major metriorhynchid subclades experienced different evolutionary pressures.
- Metriorhynchines with similar skull shapes diverged functionally, optimizing for low-stress piscivory.
More Related Videos
Related Concept Videos
01:27Cranial Bones: Lateral View
The lateral view of the cranium is dominated by temporal, sphenoid, and ethmoid bones.
The temporal bone forms the lower lateral side of the skull. The temporal bone is subdivided into several regions. The flattened upper portion is the squamous portion of the temporal bone. Below this area and projecting anteriorly is the zygomatic process of the temporal bone, which forms the posterior portion of the zygomatic arch. Posteriorly is the mastoid portion of the temporal bone. Projecting...
The temporal bone forms the lower lateral side of the skull. The temporal bone is subdivided into several regions. The flattened upper portion is the squamous portion of the temporal bone. Below this area and projecting anteriorly is the zygomatic process of the temporal bone, which forms the posterior portion of the zygomatic arch. Posteriorly is the mastoid portion of the temporal bone. Projecting...
01:07Speciation Rates
Speciation can proceed at markedly different rates, and evolutionary biologists commonly describe these differences through the models of gradualism and punctuated equilibrium. Both patterns explain how new species arise, but they differ in the tempo and continuity of evolutionary change. In both cases, evolutionary change arises from heritable variation within populations, with natural selection often shaping traits that improve survival and reproduction under specific environmental conditions.
01:54Convergent Evolution
Evolution shapes the features of organisms over time, ensuring that they are suited for the environments in which they live. Sometimes, selection pressure leads to the rise of similar but unrelated adaptations in organisms with no recent common ancestors, a process known as convergent evolution.The structures that arise from convergent evolution are called analogous structures. They are similar in function even if they are dissimilar in structure. Further, structures can be analogous while also...
01:24Evolution of New Traits in Microbes
Microorganisms evolve rapidly due to their large population sizes and short generation times, often exhibiting measurable changes within days under laboratory conditions. Natural selection acts on standing genetic variation, enabling the retention and amplification of beneficial traits that confer fitness advantages in changing environments.Adaptive Pigment Regulation in RhodobacterIn Rhodobacter, a genus of purple non-sulfur bacteria, light-harvesting pigments such as bacteriochlorophyll and...
01:14Cranial Bones: Superior and Posterior View
The superior view of the cranium shows the frontal and paired parietal bones.
The frontal bone is the single bone that forms the forehead. At its anterior midline, between the eyebrows, there is a slight depression called the glabella. The frontal bone also forms the supraorbital margin of the orbit. Near the middle of this margin is the supraorbital foramen, the opening that provides passage for a sensory nerve to the forehead. The frontal bone is thickened just above each supraorbital margin,...
The frontal bone is the single bone that forms the forehead. At its anterior midline, between the eyebrows, there is a slight depression called the glabella. The frontal bone also forms the supraorbital margin of the orbit. Near the middle of this margin is the supraorbital foramen, the opening that provides passage for a sensory nerve to the forehead. The frontal bone is thickened just above each supraorbital margin,...
01:08Overview of the Skull
The cranium (skull) is the skeletal structure of the head that supports the face and protects the brain. It is subdivided into the facial bones and the brain case, or cranial vault. The facial bones underlie the facial structures, form the nasal cavity, enclose the eyeballs, and support the teeth of the upper and lower jaws.
The cranial vault surrounds and protects the brain and houses the middle and inner ear structures. This cavity is bounded superiorly by the rounded top of the skull, which...
The cranial vault surrounds and protects the brain and houses the middle and inner ear structures. This cavity is bounded superiorly by the rounded top of the skull, which...