![]() ![]() The zygomatic bones, commonly known as the cheekbones, form the prominence of the cheeks and contribute to the structure of the eye sockets. The ethmoid bone is located between the eyes and forms part of the nasal cavity, as well as contributing to the eye sockets and skull base. The sphenoid bone is a complex bone that forms the base of the skull and contributes to the eye sockets and nasal cavity. The occipital bone forms the back of the skull, protecting the cerebellum and the visual center of the brain. The temporal bones house the ears and contain important structures like the middle and inner ear, as well as the temporal lobes of the brain. The paired parietal bones make up the sides and roof of the skull, protecting the top and sides of the brain. The frontal bone forms the forehead and protects the frontal lobes of the brain. The skull bones are connected by fibrous joints that fuse together in adulthood to form a rigid structure. ![]() The human skull comprises 22 bones, including eight cranial bones that encase and protect the brain and 14 facial bones that form the structure of the face. Rayfield, 9 September 2022, Science Advances.The skull is a complex bony structure that protects the brain. Reference: “Early tetrapod cranial evolution is characterised by increased complexity, constraint and an offset from fin-limb evolution” by James R. It seems that different factors were affecting skull and limb evolution in early tetrapods, and we have so much more to learn about this crucial time in our own evolutionary history.” Rawson concluded: “We also see a similar drop in structural variability for the limb bones in early tetrapods, but the drop in the limbs happens 10 million years earlier. ![]() We think that the evolution of a neck, extinction events, or a bottleneck in skull development may be responsible.” Professor Emily Rayfield, senior author of the study, said: “We were surprised to find these changes to the skull seemed to limit tetrapod evolution, rather than promoting radiation to new habitats on land. Modern frogs and salamanders had the most complex skulls of all the animals we studied.” The skulls of the earliest tetrapods also became more consolidated into a single unit, whereas their fish ancestors had skulls made of several distinct sections.īy looking at the variety of skull bone arrangements over time, the researchers also found that the origin of tetrapods coincides with a drop in the variety of skull bone arrangements. Rawson added: “It might seem strange, but having fewer bones means each of those bones must connect with more of its neighbors, resulting in a more complex arrangement. Network analysis provides a sound mathematical framework to quantify anatomical relations among bones: a kind of data often overlooked in most studies on morphological evolution.”Īlthough it may sound counterintuitive at first, the researchers discovered that tetrapods having fewer skull bones than fish made the organization of their skulls more complex. Borja Esteve-Altava, an expert in this technique, said: “Traditionally, anatomy research has been mostly descriptive or qualitative. We used a technique called network analysis, where the arrangement of skull bones - which bones connect to which - is recorded in addition to bone number.”Īuthor Dr. ![]() Lead author James Rawson of Bristol’s School of Earth Sciences said: “Tetrapod skulls generally have fewer skull bones than their fish ancestors, but simply counting the number of bones misses some important data. The study was conducted by researchers from the University of Bristol, Barcelona’s Universitat Pompeu Fabra, and University College London. The research, published on September 9 in the journal Science Advances, quantified the organization of skull bones in over 100 living and fossil animals to better understand how skulls changed as tetrapods evolved. ![]()
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