Ghosts of the past, present, and future in brachiopod systematics

Abstract

Three historical phases can be distinguished in the study of brachiopod systematics over the past 75 years. Prior to 1956, systematic neontologists and paleontologists struggled to reconcile differences in perceived evolutionary patterns (and thus classifications) based largely on static morphological differences observed separately among living brachiopods and among fossil brachiopods. Following 1956, patterns of morphological distribution began to be interpreted relative to the processes by which they were formed, and a more dynamic view of brachiopod phylogeny and classification resulted. Over the past decade, newer methodologies (phylogenetic systematics) have allowed older phylogenetic hypotheses to be tested and evaluated. The major challenges that brachiopod systematists now face are not unique to brachiopods; they concern improving the methods of phylogeny (and classification) reconstruction so that all the sources of data available to paleontologists can be utilized more effectively. In the future, I predict that more intensified, global fossil collecting, together with further investigation of the embryology and development of brachiopods, and molecular systematic research, will play an increasingly larger role in revising the classification currently in use.

Molecular paleobiological insights into the origin of the Brachiopoda

“…S12). Carlson (2001) notes that the craniids share approximately the same number of characters with linguliforms and rhynchonelliforms, with the problem being one of establishing polarity with respect to divergent outgroups. Embryological and neuroanatomy study on craniids also reveal a mixture of traits that make their placement uncertain (Nielsen 1991;Freeman 2000;Altenburger and Wanninger 2010).…”

Survival without recovery after mass extinctions

“…Regarding the genus-level analyses, numerical simulations have shown that paraphyly is unlikely to mask or generate major patterns of taxonomic origination and extinction, especially given the large number of taxa involved (27)(28)(29)(30)(31)(32). Order-level systematics have been increasingly cast in cladistic terms [e.g., echinoderms (33), trilobites (34), and brachiopods (35)]. Extinct orders that have not been revised from this standpoint probably represent true termination of constituent lineages in most instances, either owing to strict monophyly or because paraclades were split significantly before the last appearance of the ordinal taxon, so that the loss of that taxon is meaningful in terms of biodiversity (27)(28)(29).…”

Paterimitra pyramidalis from South Australia: scleritome, shell structure and evolution of a lower Cambrian stem group brachiopod

“…The necessity of combining research fields (e.g. palaeobiology, ecology and molecular biology) to illuminate the evolution of different animal taxa in relation to each other has been argued by many (Gould and Calloway ; Lüther and Bartholomaeus ; Carlson ; Benton and Donoghue ). In this context, studies of morphology and stratigraphic distribution of stem and crown groups (Budd and Jensen ) such as tommotiids and brachiopods provide essential data for reconstructing the tree of animal life.…”

“…Brachiopods are marine filter-feeding lophotrochozoans with a mineralized bivalved shell. They have an extensive fossil record and were among the dominant shell-bearing suspension feeders during the early Cambrian (Ushatinskaya 2001, 2008Zhang et al 2008). As members of the lophotrochozoan clade, they have been regarded as forming a monophyletic group together with the Phoronida (Cohen 2000;Cohen and Weydmann 2005;Helmkampf et al 2008;Giribet et al 2009;Santagata and Cohen 2009;Sperling et al 2011), although their exact relationship with other lophotrochozoans is still the focus of ongoing debate (Passamaneck and Halanych 2006;Helmkampf et al 2008;Yokobori et al 2008;Sperling et al 2011).…”