Table 1.
Summary of the various tissues recognized in the integumentary skeleton of nontetrapodan vertebrates. The taxa with living representatives are underlined
| Taxon | Capping tissue | Dentine | Plywood-like tissue | Bone | Comments |
|---|---|---|---|---|---|
| Pteraspidomorphi | enameloid/none | orthodentine/ mesodentine/none | lamellar bone* | acellular bone† | odontodes |
| Anaspida | ? | ? | lamellar bone* | acellular bone† | ? odontodes |
| Thelodonti | enameloid | orthodentine | none | acellular bone† | odontodes |
| Galeaspida | none | none | lamellar bone* | acellular bone† | – |
| Osteostraci | enameloid/none | mesodentine | lamellar bone* | cellular bone | cosmoid-like organization with putative odontodes |
| Placodermi | none | semidentine/ orthodentine/none | none | cellular bone | odontode-like derivatives |
| Chondrichthyes | enameloid | orthodentine | none | acellular bone | odontodes |
| Acanthodii | ganoine/none | mesodentine/ orthodentine | none | acellular bone/cellular bone | odontode-like squamation |
| Andreolepis | ganoine (monolayered) | orthodentine | none | cellular bone | palaeoniscoid-type ganoid scale |
| Cheirolepis | ganoine (multilayered) | orthodentine | none | cellular bone | palaeoniscoid-type ganoid scale |
| Cladistia | ganoine (multilayered) | orthodentine | elasmodine | cellular bone | polypteroid-type ganoid scale |
| Moythomasia | ganoine (multilayered) | orthodentine | none | cellular bone | palaeoniscoid-type ganoid scale |
| Chondrostei | ganoine/none | none | none | cellular bone | lepisosteoid-type ganoid scale/bony plate |
| Lepisosteiformes | ganoine (multilayered) | none | none | cellular bone | lepisosteoid-type ganoid scale |
| Amiiformes | ganoine/limiting layer | orthodentine/external layer | elasmodine/lamellar bone | cellular bone/none | ganoid to elasmoid scale |
| Teleostei | limiting layer | external layer | elasmodine | acellular bone/cellular bone/none | elasmoid scales, bony plates or scutes |
| Porolepiformes | enamel(oid)/limiting layer | orthodentine/external layer | elasmodine/lamellar bone | cellular bone/none | cosmoid |
| Dipnoi | enamel(oid)/limiting layer | orthodentine/external layer | elasmodine/lamellar bone | cellular bone/none | cosmoid to elasmoid scale |
| Actinistia | enamel(oid)/limiting layer | orthodentine/external layer | elasmodine/lamellar bone | cellular bone/none | cosmoid to elasmoid scale |
*
In these taxa the lamellar bone of the basal plates has been called ‘isopedine’.
†
In these early vertebrates the ‘aspidin’ is very similar to acellular bone.