| Brachiopoda | ||
| Brachiopoda | Dendrogram |
| Metazoa | |||
|
Lophotrochozoa
├─Bryozoa
└─Halkieriida
├─Mollusca
└─┬─Annelida
└─┬─Tommotiida
└─Brachiopoda
├─Linguliformea
└─┬─Craniiformea
└─Rhynchonelliformea
|
Introduction |
The following very useful diagram is from Senckenberg Research Institute, Frankfurt
The bottom row lists the three subkingdoms, the next the classes, and finally the time-line and phylogeny shows the orders, along with represemntative illustrations. Many of these ordinal groups are likely paraphyletic, as shown here. However the exact relationships of some of these taxa remains speculative (and hence are usefully represented by evolutionary systematic style dotted lines)
The following dendrogram is based on this phylogeny (from Access Science). It gives the illusion that brachiopod systematics and phylogeny is pretty well worked out. Nothing could be further from the truth. Endemic homoplasy means that, above superfamily level, exact phylogenetic relationshiops remain frustratingly unclear. The only difference is that we have retained the three main clades (with Phoronida as a fourth one) as an unresolved polytomy. It is likely that proto-brachiopods radiated rapidly at this time, (at the start of the Cambrian explosion), making precise phylogenetic determination difficulat (and always, morphology may give one version, molecular phylogeny another, and differemnt molecular phylogenies different topologies). Especially, the positions of a number of taxa (e.g. Phoronida, Thecideida) is difficult to determine. MAK120107