Environmental differentiation reflected by vertebrate faunal diversity in the Lower Devonian of the Holy Cross Mountains, Poland

Abstract

As so ci ate Ed i tor: Micha³ ZatoñThe Lower De vo nian of the Holy Cross Moun tains is well-known in the field of ver te brate palae on tol ogy but re mains un rec ognized as re gards palaeoenvironmental re con struc tions. We there fore ana lysed the spa tial dis tri bu tion and rel a tive abundance of fos sil ver te brates in this area within one time in ter val. The fauna from an Early De vo nian (Emsian) siliciclastic bone-bear ing brec cia (the "Placoderm Sand stone") ex posed in four sec tions of the £ysogóry re gion and five sec tions of the Kielce re gion was ana lysed with re spect to the fre quency of the re mains and their tax o nomic af fin ity. The rel a tive abundances of agnathans, ac an tho dians, placoderms, osteichthyans and chondrichthyans sug gest more open ma rine con di tions in the £ysogóry re gion and more ter res trial-in flu enced in the Kielce re gion dur ing the Emsian. The re sults show that the av erage agnathan and ac an tho dian con tent of the £ysogóry re gion is sig nif i cantly larger than that in the Kielce re gion. On the other hand, there are rel a tively fewer osteichthyans in the £ysogóry re gion and a sig nif i cantly higher pro por tion of bony fishes was re corded in the fauna of the Kielce re gion. Placoderms are char ac ter ized by their gen er ally sim i lar fre quency in both regions and from site to site in each of them, though a greater abun dance was noted from the Kielce re gion. Like wise dif ferences in the pro por tions of par tic u lar groups in the Kielce re gion sug gest a large va ri ety of mar ginal-ma rine en vi ron ments un der the in flu ence of fac tors that might have in cluded ma rine cur rents and vari able con di tions around a river mouth.