Morphometrics, growth characteristics, and phylogenetic implications ofHalysites catenularius(Tabulata, Silurian, Estonia)

Abstract

AbstractBased on multivariate morphometric analysis,Halysites catenulariusis identified from the Rumba Formation (Telychian) and Jaagarahu Formation (Sheinwoodian) of Estonia;H. priscusis confirmed as a junior synonym.Halysites catenularius,H.junior, andH.seniorare shown to be closely related;H.catenulariusis morphologically intermediate. Cyclomorphism inH.catenularius, recorded by fluctuations of corallite tabularial area, indicates an average annual growth rate of 6.0 mm, which is typical for halysitids. Tubules inH.catenularius, generated from small intramural openings between adjacent corallites, were involved in two types of interstitial increase. The intramural openings, three types of lateral increase, temporary agglutinated patches of corallites, and axial increase documented inH. catenulariusresemble features in some species ofCatenipora. These similarities are consistent with the interpretation thatHalysitesevolved fromCatenipora. Evaluation of the possibility that both genera are polyphyletic will require further detailed analysis of additional species.