Contribution
Constructional morphology and evolutionary ecology of Sand Dollars
Seilacher, Adolf
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen Band 157 Heft 1-2 (1978), p. 169 - 172
1 références bibliographiques
publié: Dec 11, 1978
DOI: 10.1127/njgpa/157/1978/169
ArtNo. ESP155015701025, Prix: 29.00 €
Abstract
Among the irregular echinoids, sand dollars are set apart by a number of key features (flat test, sieve spines) that enabled them to enter the new nutritional zone of vagile, endobenthic sand sievers. They have evolved from less specialized clypeasteroid ancestors at least three times in geographically isolated lineages (Figs. 1—2): (1) As Scutellina in the Caribbean, (2), as Rotulidae in W-Africa, (3) as Arachnoididae in Australia. Their further phylogenetic differentiation was more the result of their migrational history than of niche partitioning. It is most pronounced in the Scutellina, whose early origin and paleogeographic opportunities favored a circum-global distribution. Since earlier migration routes became cut off by geodynamic (Panamanian land bridge; opening of the Atlantic; Mid-Eastern partition of the Tethys) and climatic events, their expansion remained largely unidirectional. Only after the collision of the Australian plate could the eastern branch of the Scutellina get in competitional contact with the Arachnoididae, as they did in Japan with their own kinship of the western branch.
Mots-clefs
morphology • evolutionary ecology • Sand Dollars