Related Experiment Video
Updated: Nov 19, 2025
08:02
Dissection and Flat-mounting of the Threespine Stickleback Branchial Skeleton
Published on: May 7, 2016
10.1K
Evolution of forelimb musculoskeletal function across the fish-to-tetrapod transition
J L Molnar1, J R Hutchinson2, R Diogo3
1Anatomy Department, New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, Old Westbury, NY 11568, USA. julia.molnar@nyit.edu spierce@oeb.harvard.edu.
Science Advances
|February 1, 2021
Summary
Early tetrapods evolved unique forelimb function for land locomotion. This involved restricted rotation, enhanced retraction, and greater elbow mobility, differing from modern animals.
Area of Science:
- Vertebrate Evolution
- Paleontology
- Biomechanics
Background:
- Understanding tetrapod land locomotion is key to vertebrate evolution.
- Few hypotheses on the fin-to-limb transition are fossil-tested.
Purpose of the Study:
- Quantitatively examine pectoral appendage function during the fin-to-limb transition.
- Investigate forelimb functional changes in early tetrapods.
Main Methods:
- Constructed 3D musculoskeletal models of pectoral appendages in *Eusthenopteron*, *Acanthostega*, and *Pederpes*.
- Compared fossil tetrapod forelimb function with extant fishes and tetrapods.
Main Results:
- Early tetrapods exhibited restricted humerus rotation and enhanced humeral retraction.
- Increased elbow flexion-extension mobility was observed in early tetrapods.
- Forelimb specializations for weight support appeared later than those for substrate interaction.
Conclusions:
- Early tetrapod forelimb evolution prioritized limb-substrate interactions over weight support.
- A unique ancestral locomotor mode resulted from competing aquatic and terrestrial pressures.
Related Concept Videos
01:09Changes in the Appendicular Skeleton with Age
3.1K
The upper and lower limb initially develops as a small bulge called a limb bud, which appears on the lateral side of the early embryo. The upper limb bud appears near the end of the fourth week of development, with the lower limb bud appearing shortly after.
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...
3.1K
01:54Convergent Evolution
30.5K
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.
30.5K
02:35What is Evolutionary History?
41.9K
Scientists record evolutionary history by analyzing fossil, morphological, and genetic data. The fossil record documents the history of life on Earth and provides evidence for evolution. However, both fossil and living organisms offer evidence that outlines Earth’s evolutionary history.
41.9K
02:55The Evidence for Evolution
46.2K
Genetic variations accumulating within populations over generations give rise to biological evolution. Evolutionary changes can result in the formation of novel varieties and entire new species. These changes are responsible for the diverse forms of life inhabiting the planet. The evidence for evolution suggests that all living organisms descended from common ancestors.
46.2K
01:07Development of the Limb Synovial Joints
1.9K
Joints form during embryonic development in conjunction with the formation and growth of the associated bones. The embryonic tissue that gives rise to all bones, cartilage, and connective tissues of the body is called mesenchyme.
The mesenchymal stem cells differentiate into chondrocytes that form the hyaline cartilage, and later the cartilaginous model of the bone. This model further transforms into a bone. This process is known as endochondral ossification.
During development, the limbs...
The mesenchymal stem cells differentiate into chondrocytes that form the hyaline cartilage, and later the cartilaginous model of the bone. This model further transforms into a bone. This process is known as endochondral ossification.
During development, the limbs...
1.9K
02:56The Fossil Record
26.6K
The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...
26.6K