Date de création : 2014 - Dernière mise à jour : 11 mars 2014
The computer-aided knowledge base is composed by the 307 genera considered to be valid at present. Concerning the geographical repartition it is a world-wide scale. Stratigraphical extension contains all the Cambrian even if most of Archaeocyatha lived during lower Cambrian.
Each genus is illustrated with types specimens and sometimes with additional specimens better preserved. 120 descriptors are used:
· 85 corresponding to morphological and ontogenetic data
· 8 to stratigraphic and geographic data
· 27 to taxonomic data.
To each descriptor and character state we associated a definition and pictures and/or sketches.
The literature was consulted and analysed to collect most of characters proposed by paleontologists to identify archaeocyath’s genera (Debrenne & al., 1990; Debrenne & Zhuravlev, 1992; Debrenne & al., 2002).
This task was completed by some discussions with Françoise Debrenne and the observation of about 1000 specimens in the MNHN’s collections which contains about 600 types and figurative.
In the identification unit, some distinctive features appear:
· A presence of descriptors without taxonomic interest
· A partial new terminology: some descriptors names can be different from usual ones. (see comparison)
Two main reasons explain these choices:
· The knowledge base has to be accessible for a large public:
o Characters without taxonomic significance are present because they often can be seen easily.
o Descriptors names should be easily understand.
· In usual terminology, one term can imply several basic descriptors. Here we try using only basic descriptors (i.e.: compound wall means a wall has two different parts: a carcass and a additional sheath)