- Kröger, Björn (March 2007). "Early growth‐stages and
classification of
orthoceridan Cephalopods of the
Darriwillian (Middle Ordovician) of Baltoscandia"...
- brachiopods, bivalves, forams,
ammonoids (including goniatites), and
orthoceridans all abundant.
Crown reptiles arise from
earlier diapsids, and split...
- S2CID 128629737. Kröger, Björn (2006). "Early growth-stages and
classification of
orthoceridan cephalopods of the
Darriwillian (Middle Ordovician) of Baltoscandia"...
- 623:1-81 Kröger, Björn; Isakar, Mare (2006). "Revision of
annulated orthoceridan cephalopods of the
Baltoscandic Ordovician".
Fossil Record. 9 (1): 137–163...
- S2CID 4409157. Kröger, Björn (2006). "Early growth-stages and
classification of
orthoceridan Cephalopods of the
Darriwillian (Middle Ordovician) of Baltoscandia"...
- New
Mexico Kröger, Bjorn, & Isakar, Mare. (2006)
Revision of
annulated orthoceridan cephalopods of the
Baltoscandic Ordovician.
Fossil Record 9(1):137-163...
