the scientific journal Nature. Due to their lobed fins and other features, it was once hypothesized that the coelacanth might be the most recent shared ancestor between terrestrial and marine vertebrates. But after sequencing the full genome of the coelacanth, it was discovered that the lungfish is the most recent shared ancestor. Coelacanths and lungfish had already diverged from a common ancestor before the lungfish made the transition to land. Another important discovery made from the genome sequencing is that the coelacanths are still evolving today. While phenotypic similarity between extant and extinct coelacanths suggests there is limited evolutionary pressure on these organisms to undergo morphological divergence, they are undergoing measurable genetic divergence. Despite prior studies showing that protein coding regions are undergoing evolution at a substitution rate much lower than other tetrapods (consistent with phenotypic stasis observed between extant and fossil members of the taxa), the non-coding regions subject to higher transposable element activity show marked divergence even between the two extant coelacanth species. This has been facilitated in part by a coelacanth-specific endogenous retrovirus of the Epsilon retrovirus family. Taxonomy Cladogram showing the relationships of coelacanth genera after Torino, Soto and Perea, 2021. Fossil record According to the fossil record, the divergence of coelacanths, lungfish and tetrapods is thought to have occurred during the Silurian. Over 100 fossil species of coelacanth have been described. The oldest identified coelacanth fossils are around 420-410 million years old, dating to the early Devonian. Coelacanths were never a diverse group in comparison to other groups of fish, and reached a peak diversity during the Early Triassic (252-247 million years ago), coinciding with a burst of diversification between the Late Permian and Middle Triassic. Most Mesozoic coelacanths belong to the order Latimerioidei, which contains two major subdivisions, the marine Latimeriidae, which contains modern coelacanths, as well as the extinct Mawsoniidae, which were native to brackish, freshwater as well as marine environments. Paleozoic coelacanths are generally small (~30–40 cm in length), while Mesozoic forms were larger. Several specimens belonging to the Jurassic and Creataceous mawsoniid coelcanth genera Trachymetopon and Mawsonia likely reached or exceeded in length, making them amongst the largest known fishes of the Mesozoic, and amongst the largest bony fishes of all time. The most recent fossil latimeriid is Megalocoelacanthus dobiei, whose disarticulated remains are found in late Santonian to middle Campanian, and possibly earliest Maastrichtian-aged marine strata of the Eastern and