| Basic info | Taxonomic history | Classification | Included Taxa |
| Morphology | Ecology and taphonomy | External Literature Search | Age range and collections |
Bistarkum rigidium
Description: Rays about equal in length, medium of width, one ray usually slightly wider than the other, both rays terminating in large ellipsoidal tips. Width of tips about equal to length of ray shafts. Test comprised of small irregularly arranged polygonal pore frames without prominent small nodes at vertices. Several spines with circular cross-section and variable length occurring at distal surface of tips and sides of rays.
Remarks: Bistarkum rigidium Yeh, differs from B. bifurcum Yeh, by lacking bifurcate tips and by having a wider test.
Etymology: Rigidius-a-um (Latin, adj.) rigid.
| Year | Name and author |
|---|---|
| 1987 | Bistarkum rigidium Yeh p. 43 figs. Pl. 1, fig. 5; Pl. 21, fig. 5; Pl. 22, figs. 1, 3, 7, 11 |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
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| Source: p = phylum | |||||
| Reference: Kiessling 1999 | |||||
Age range: base of the Late/Upper Pliensbachian to the top of the Early/Lower Toarcian or 189.60000 to 182.00000 Ma
Collections (4 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Late/Upper Pliensbachian | USA (Oregon) | Bistarkum rigidium (124323) | |
| Early/Lower Toarcian | USA (Oregon) | Bistarkum rigidium (124331 type locality: 124334) | |
| Early/Lower Toarcian | Japan | Bistarkum rigidium (124830) |