Page "Bryozoa" Paragraph 5

Mineralized skeletons of bryozoans first appear in rocks from latest Cambrian period, about, making it the last major phylum to appear in the fossil record.

This has led researchers to suspect that bryozoans had arisen earlier but were initially unmineralized, and may have differed significantly from fossilized and modern forms.

Early fossils are mainly of erect forms, but encrusting forms gradually became dominant.

It is uncertain whether the phylum is monophyletic.

Bryozoans ' evolutionary relationships to other phyla are also unclear, partly because scientists ' view of the family tree of animals is mainly influenced by better-known phyla.

Both morphological and molecular phylogeny analyses disagree over bryozoans ' relationships with entoprocts, about whether bryozoans should be grouped with brachiopods and phoronids in Lophophorata, and whether bryozoans should be considered protostomes or deuterostomes.