Tertiary and Mesozoic Echinoids of Saudi Arabia

Abstract

The Mesozoic and Tertiary echinoids are described from Saudi Arabia. Fifty-one species, thirty-four of them new, occur in beds ranging from the Lower Jurassic to the Miocene. Two species are present in the Lower Jurassic (Toarcian) Marrat Formation, one is new: <i>Acrosalenia marratensis</i>. The Middle Jurassic (Bajocian-Bathonian) middle Dhruma Formation yielded eleven species, all new: <i>Acrosalenia arabica, Acrosalenia dhrumaensis, Heterosalenia dhrumaensis, Pseudocidaris depressa, Polycyphus arabicus, Pseudosalenia magniprocta, Farquharsonia crenulata, Leioechinus namus</i> (type species of new genus of the family Stomechinidae), <i>Plesiechinus altus, Bothryopneustes arabica</i>, and <i>Bothryopneustes dhrumaensis</i>. Thirteen species are described from the Late Jurassic (Callovian) upper Dhruma Formation, including twelve new species: <i>Acrosalenia bowersi, Pseudocidaris romani, Pseudocidaris raratuberculata, Hypodiadema nanituberculata, Heterosalenia brocki, Heterosalenia ornata, Leioechinus amplus, Polycyphus parvituberculatus, Holectypus phelani, Pygurus (Pygurus) arabicus, Bothryopneustes kauffmani</i>, and <i>Bothryopneustes inflata</i>. One species, <i>Bothryopneustes orientalis</i> Fourtau, occurs in the Callovian Tuwaiq Mountain Limestone. Eleven species are reported from the Late Cretaceous (Campanian or Maestrichtian) Aruma Formation, five of which are new. <i>Rhynchopygus arumaensis, Proraster granti, Iraniaster bowersi, Iraniaster affinimorgani</i>, and <i>Iraniaster affinidouvillei</i>. The sympatric pairing of two species of <i>Iraniaster</i> corresponds to a pairing of another two species of this genus in the Senonian of Iran. This pairing has been reported in living spatangoids. The Early Cretaceous Yamama Formation yielded the new species <i>Pygurus (Pygurus) yamamaensis</i>. Beds of Eocene or Oligocene age yielded three echinoid species, one of them new: <i>Agassizia arabica</i>. Nine species occur in the Miocene Dam Formation, three are new: <i>Schizechinus pentagonus, Fibularia damensis</i>, and <i>Agassizia powersi</i>. These Miocene echinoids are quite similar to species now living in the littoral zone. The distribution and affinities of the echinoid species indicate faunal provinces in the Jurassic largely confined to Saudi Arabia, and in the Cretaceous confined to Saudi Arabia and Iran with some connections to North Africa but not to India. The Miocene distribution differs in being a part of a fauna occurring along the present borders of the Persian Gulf and the Arabian Sea of Saudi Arabia, Iran, West Pakistan, and northwestern India.