Vogelgnathus variabilis (Dzik, 2006) from the early Famennian K. triangularis Zone at Jabłonna in the Holy Cross Mountains.

Diagnoza

M elements with relatively short and transversely arranged inner process; cusp of P₁ element only slightly longer than other denticles.

Porównanie

This is the geologically oldest species of the genus. Its unusual variability and small size suggests a paedomorphic origin and release of selection pressure on the apparatus morphology. Possibly the associated Mehlina kielcensis sp. n. is close to its ancestor, as suggested by similar M and P₁ elements but other elements of the apparatus are non-paedomorphic. Alternative to this ancestry is the relationship to Pandorinellina? vogelgnathoides but this would require a cryptic occurrence of the latter lineage during the K. triangularis Zone. As generally the francodinids show punctuated distribution, this is not unlikely.

In late populations of the species  most M elements show a rounded tip of the external process, which is typical for its successor, V. proclinatus.

Autekologia

Występowanie geograficzne

Płucki and Jabłonna.

Zasięg czasowy

The K. triangularis Zone

Materiały muzealne

ZPAL: 748 specimens.

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.