First record of non-mineralized cephalopod jaws and arm hooks from the latest Cretaceous of Eurytania, Greece

Abstract

Due to the lower fossilization potential of chitin, non-mineralized cephalopod jaws and arm hooks are much more rarely preserved as fossils than the calcitic lower jaws of ammonites or the calcitized jaw apparatuses of nautilids. Here, we report such non-mineralized fossil jaws and arm hooks from pelagic marly limestones of continental Greece. Two of the specimens lie on the same slab and are assigned to the Ammonitina; they represent upper jaws of the aptychus type, which is corroborated by finds of aptychi. Additionally, one intermediate type and one anaptychus type are documented here. The morphology of all ammonite jaws suggest a desmoceratoid affinity. The other jaws are identified as coleoid jaws. They share the overall U-shape and proportions of the outer and inner lamellae with Jurassic lower jaws of Trachyteuthis (Teudopseina). We also document the first belemnoid arm hooks from the Tethyan Maastrichtian. The fossils described here document the presence of a typical Mesozoic cephalopod assemblage until the end of the Cretaceous in the eastern Tethys.

Offshore marine actinopterygian assemblages from the Maastrichtian–Paleogene of the Pindos Unit in Eurytania, Greece

“…The overall character of the sampled fossil assemblages in the vicinity of Karpenisi is congruent with an open, deep water depositional environment, also inferred by the platy limestone and calcareous marl sedimentation, which includes an abundance of planktonic foraminifera ( Koch & Nicolaus, 1969 ; Fleury, 1980 ). Macroinvertebrates are generally scarce, with only poorly preserved †desmoceratid, or otherwise indeterminate ammonite shell traces found in SGL1 and nearby sites ( Klug et al, 2020 ). Interestingly, several non-mineralized ammonite and coleoid jaws have been collected ( Klug et al, 2020 ), exhibiting the rare potential of these transitional marly facies to preserve soft tissues, which can in turn be linked with low bottom oxygen levels and rapid burial.…”

“…Macroinvertebrates are generally scarce, with only poorly preserved †desmoceratid, or otherwise indeterminate ammonite shell traces found in SGL1 and nearby sites ( Klug et al, 2020 ). Interestingly, several non-mineralized ammonite and coleoid jaws have been collected ( Klug et al, 2020 ), exhibiting the rare potential of these transitional marly facies to preserve soft tissues, which can in turn be linked with low bottom oxygen levels and rapid burial. Low bottom oxygenation is further supported by the absence of benthic organisms in the sampled strata.…”

“…The examined Maastrichtian fish-bearing horizons have not yielded fossils of deep bodied groups (e.g., †pycnodonts) and other bottom feeding or grazing fishes, which are more common in shallow water settings, suggesting that the “transitional facies to the flysch” of the Pindos Unit in Eurytania were not in the immediate paleogeographic vicinity of shallow reefal or epicontinental sea habitats (see Jebel Tselfat ( Khalloufi, Ouarhache & Lelièvre, 2010 ), or Lebanese deposits ( Forey et al, 2003 ) for examples, of more nearshore open water faunas containing possibly transported shallow water faunal elements). Macropredation is the main ecological theme suggested by the dentitions of most collected fossil fishes, and the presence of soft-bodied nektonic cephalopod remains in SGL1—as a possible source of food for fishes ( Klug et al, 2020 )—illuminate aspects of Maastrichtian food chain complexity in Eurytania. A synthesis of available fossil and lithological evidence points towards the presence of fully functional open marine ecosystems in the depositional environments of the Pindos Unit, and Tethys as a whole, right before the K–Pg Extinction event.…”

“…Distinctive thin layers of marly limestones, which overly the Plattenkalk, acting as harbingers of flysch sedimentation, can be recognized along the Pindos belt and are historically and informally referred to by geologists as the “transitional layers to the flysch” ( Fleury, 1980 ). In Eurytania, these laminated marly layers contain fossils of ray-finned fishes, chondrichthyans, as well as cephalopod beaks and rare, poorly preserved ammonite shells ( Koch & Nicolaus, 1969 ; Klug et al, 2020 ; this work). These transitional, marly facies in the vicinity of Karpenisi were dated to the late Maastrichtian–Danian, on the basis of the presence of the planktonic foraminifer † Contusotruncana (=† Globotruncana ) contusa ( Koch & Nicolaus, 1969 ), or, more precisely, to the late Maastrichtian (~70–67 Ma) on the basis of a more diverse planktonic foraminiferal sample, including: † Contusotruncana (=† Globotruncana ) contusa ; † Globotruncana falsostuarti ; † Globotruncana gansseri ; † Globotruncanita (=† Globotruncana ) stuarti ( Fleury, 1980 ; taxonomy and biostratigraphic ranges updated sensu Huber & Petrizzo, 2019 ).…”

“…and some indeterminate ammonites associated with fish fossils ( Klug et al, 2020 ), which exclude a Danian age for the latter. Non-mineralized ammonite and coleoid jaws were also recovered from the same horizons ( Klug et al, 2020 ). An additional locality, AND, is located on the banks of Aniada Creek, near the dirt road from Aniada to Vythisma (38°48′23.82″N; 21°48′32.12″E).…”