000145576 001__ 145576 000145576 005__ 20241108105822.0 000145576 0247_ $$2doi$$a10.1146/annurev-earth-031621-113343 000145576 0248_ $$2sideral$$a140384 000145576 037__ $$aART-2024-140384 000145576 041__ $$aeng 000145576 100__ $$aRahman, Imran A. 000145576 245__ $$aOrigin and Early Evolution of Echinoderms 000145576 260__ $$c2024 000145576 5060_ $$aAccess copy available to the general public$$fUnrestricted 000145576 5203_ $$aEchinoderms are a major group (phylum) of invertebrate animals with a rich fossil record stretching back to the Cambrian period, approximately 518 million years ago. While all modern species are characterized by pentaradial (i.e., fivefold) symmetry, Cambrian echinoderms also include taxa with different types of symmetry (e.g., bilateral symmetry). These distinct forms were present from very early in the phylum's history, demonstrating that the initial diversification of echinoderm body plans was extremely rapid. The phylogenetic relationships of Cambrian echinoderms have long been debated, hindering efforts to reconstruct the evolution of the phylum, but recent analyses have consistently recovered bilaterally symmetrical forms as the earliest-diverging echinoderms. This reveals the sequence of character acquisition in echinoderm evolution, indicating that radial symmetry is a derived character of the group, which evolved after the acquisition of a mineralized skeleton. Cambrian echinoderms were adapted to diverse modes of life, with ecology an important factor shaping their early evolution. However, the reasons why echinoderms evolved their unique pentaradial body plan remain unclear. ▪The Cambrian fossil record provides valuable insights into the origin and early evolution of echinoderms over half a billion years ago.▪Cambrian echinoderms were morphologically diverse, with several extinct groups exhibiting character combinations that distinguish them from living species.▪Phylogenetic analyses of bilateral, asymmetrical, triradial, and pentaradial fossils have allowed us to decipher the assembly of the modern echinoderm body plan.▪Echinoderms became ecologically diverse early in their history, with varied modes of feeding, locomotion, and attachment. 000145576 536__ $$9info:eu-repo/grantAgreement/ES/DGA/E18-17R$$9info:eu-repo/grantAgreement/ES/MICINN/PID2021-125585NB-I00 000145576 540__ $$9info:eu-repo/semantics/openAccess$$aby$$uhttp://creativecommons.org/licenses/by/3.0/es/ 000145576 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/publishedVersion 000145576 700__ $$0(orcid)0000-0002-3917-4628$$aZamora, Samuel 000145576 773__ $$g52, 1 (2024), 295-320$$pAnnu. rev. earth planet. sci.$$tANNUAL REVIEW OF EARTH AND PLANETARY SCIENCES$$x0084-6597 000145576 8564_ $$s10887471$$uhttps://zaguan.unizar.es/record/145576/files/texto_completo.pdf$$yVersión publicada 000145576 8564_ $$s1760056$$uhttps://zaguan.unizar.es/record/145576/files/texto_completo.jpg?subformat=icon$$xicon$$yVersión publicada 000145576 909CO $$ooai:zaguan.unizar.es:145576$$particulos$$pdriver 000145576 951__ $$a2024-11-08-10:38:18 000145576 980__ $$aARTICLE