All articles tagged with #vertebrate evolution
Fossils from the Cambrian Chengjiang beds in China show that early vertebrates called myllokunmingids had four eyes—two large on the sides and two smaller in between—likely giving them a wider field of view to dodge predators; the two smaller eyes may be ancestral to image-forming eyes linked to the pineal gland, offering new insights into how vertebrate vision evolved.
Researchers using synchrotron X-ray imaging analyzed 443-million-year-old Jamoytius and Lasanius fossils found near Glasgow. They discovered bone-like tissues and traces of zinc and copper in the eyes, indicating advanced camera-type eyes and early bone development in vertebrates, pushing back the origin of these features. The study, published in Proceedings of the Royal Society B, suggests these early vertebrates were less primitive than previously thought.
Fossil evidence from about 518 million years ago suggests the earliest vertebrates had four image-forming eyes—two extra on top of the head—reshaping our understanding of how camera-type eyes evolved in vertebrates.
Scientists discovered that male spotted ratfish have true teeth on a forehead appendage used in mating, challenging long-held beliefs that teeth are only located in the mouth. This structure, called the tenaculum, is a rare example of non-oral teeth in vertebrates, providing new insights into dental evolution and developmental biology.
The article discusses the convergent evolution of diverse jaw joints in mammaliamorphs, supported by fossil data, digital reconstructions, and phylogenetic analysis, highlighting evolutionary adaptations in mammalian jaw structures.
The article presents a novel non-destructive synchrotron imaging study of the fossil Norselaspis glacialis, revealing new insights into the head-trunk interface and circulatory system of early vertebrates, bridging features between jawless and jawed vertebrates, and challenging previous reconstructions of its anatomy.
A new study revises the understanding of coelacanth fish anatomy, revealing that many previously thought evolutionary muscle features are actually ligaments, which reshapes our view of vertebrate skull evolution and shows coelacanths are more similar to sharks and tetrapods than previously believed.
Scientists discovered a 346-million-year-old fossil, Westlothiana lizziae, in Scotland, providing new insights into early vertebrate evolution and the transition of life from water to land, filling a crucial gap in the fossil record known as Romer's Gap.
Researchers have debunked a long-held belief that lamprey, a type of jawless fish, lack sympathetic neurons, which are part of the peripheral nervous system. New research led by Marianne Bronner's lab at Caltech has found that sympathetic neurons do exist in lamprey but arise much later in development than previously thought, revising the timeline of sympathetic nervous system evolution. This discovery suggests that the developmental program governing the formation of sympathetic neurons is evolutionarily conserved across all vertebrates, from lamprey to mammals.
A study published in Cell reveals that ancient retroviruses are responsible for the development of myelin, a crucial component of complex vertebrate brains. The discovery of "RetroMyelin," a gene sequence derived from ancient retroviruses, highlights the impact of viral genes on vertebrate evolution. Experimental disruption of RetroMyelin in zebrafish and frogs led to significantly reduced myelin production, demonstrating its functional role in myelination across mammals, amphibians, and fish. This research challenges previous understandings of evolutionary biology and opens new avenues for exploring the intricate relationship between viruses and vertebrate development.
The sequencing and analysis of the genome of the inshore hagfish, Eptatretus burgeri, sheds light on the timing and consequences of whole-genome duplication events in early vertebrate evolution. The study provides insights into the ancestral vertebrate karyotype, supports the monophyly of cyclostomes, and reveals the presence of six Hox clusters in hagfish, suggesting a distinct genome history shared by lampreys and hagfish. Additionally, the research uncovers gene family evolution and genomic changes accompanying major transitions in chordate evolution, offering essential information for comparative genomics and understanding the genetic basis of vertebrate diversity.
Fossil evidence from the braincase of an Early Devonian placoderm fish suggests a pharyngeal basis for the origin of the vertebrate shoulder girdle. The findings support the archipterygium hypothesis, which proposes that fins and girdles evolved from an ancestral gill arch. The study combines computed tomography scanning with comparative anatomy of placoderms and jawless outgroups to locate the origin of the pectoral girdle on the sixth branchial arch. These findings provide a new framework for understanding the evolution of the pectoral girdle and help reconcile the archipterygium hypothesis with the ventrolateral fin-fold model.
A 455-million-year-old fossil of the jawless fish Eriptychius americanus has provided new insights into the evolution of vertebrate skulls. The fossil, discovered in Colorado, is the oldest 3D evidence of cranial anatomy in an early vertebrate. The skull arrangement of E. americanus is unlike anything seen in living vertebrates or its extinct relatives, with unfused cartilage sections surrounding the mouth, olfactory organs, and eyes. CT scans allowed researchers to visualize the cartilage and reconstruct a digital model of the fish's cranium. The fossil fills a gap in our understanding of vertebrate head evolution and provides valuable insights into the ancient jawless fish's anatomy.