Ligonodina pectinata from the K. triangularis Zone at Jabłonna  in the Holy Cross Mountains.

Apparatus composition of Ligonodina pectinata.

Diagnoza

Prominently denticulated dorsal process and large triangular cusp of the M element, relatively shallow basal cavities of all elements

Porównanie

Identification of this species in the earliest Famennian is based on rather weak evidence: one juvenile M element from sample Pł-40, which may be an extreme variety of Ctenopolygnathus and a robust but teratologically deformed specimen from sample Pł-1. This refers also to the generalized prioniodinids from the K. triangularis Zone at Jabłonna . In younger Famennian strata from other localities much more derived prioniodinids are represented. Unfortunately, other elements in the apparatus are usually of little diagnostic value and even if several names are available for the Famennian prioniodinids. From the same reason several occurrences of the species are identified only tentatively.

In the Frasnian populations of the species there is some uncertainty regarding distinction between S₁ and P₁ elements, both showing a wide population variability. Position in the apparatus of the elements with short and strongly twisted ventral process and relatively high cusp  remains controversial. In the latest Frasnian samples undoubted P₁ elements have been identified , with robust denticles, a high cusp, and arched dorsal process. In the Famennian their homologues show a less prominent denticulation but more blade-like appearance. This may be a case of directional evolution.

In the basalmost Famennian sample at Miedzianka (Md-27) wide M elements closely similar to those of L. albidens Dzik, 2006 co-occur with robust S_3-4 elements resembling somewhat those of Idioprioniodus uncadinoides Dzik, 2006. This may be a population transitional between L. pectinata and L. albidens but the material (conglomerate!) may contain reworked Frasnian specimens as well.

Autekologia

Występowanie geograficzne

Płucki
Jabłonna and Miedzianka

Zasięg czasowy

Only the earliest Famennian
Possibly also the late K. triangularis Zone

Materiały muzealne

ZPAL: 419 specimens, some of doubtful specific affinity

Literatura

Dzik, J. 2006. The Famennian "Golden Age" of conodonts and ammonoids in the Polish part of the Variscan sea. Palaeontologia Polonica 63, 1-359.