New insights on the shell-crusher shark Ptychodus decurrens Agassiz, 1838 (Elasmobranchii, Ptychodontidae) based on the first known articulated dentition from the Upper Cretaceous of Croatia

Abstract A new lower tooth plate of Ptychodus decurrens from the Turonian (Upper Cretaceous) of the Dalmatian region (southern Croatia) is documented here for the first time. The specimen represents the first articulated dentition of a ptychodontid shark that has been discovered from the Balkan Peni...

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Main Authors: Manuel Amadori, Sanja Japundžić, Jacopo Amalfitano, Luca Giusberti, Eliana Fornaciari, Patrick L. Jambura, Jürgen Kriwet
Format: Article
Language:English
Published: SpringerOpen 2025-01-01
Series:Swiss Journal of Palaeontology
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Online Access:https://doi.org/10.1186/s13358-024-00340-7
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author Manuel Amadori
Sanja Japundžić
Jacopo Amalfitano
Luca Giusberti
Eliana Fornaciari
Patrick L. Jambura
Jürgen Kriwet
author_facet Manuel Amadori
Sanja Japundžić
Jacopo Amalfitano
Luca Giusberti
Eliana Fornaciari
Patrick L. Jambura
Jürgen Kriwet
author_sort Manuel Amadori
collection DOAJ
description Abstract A new lower tooth plate of Ptychodus decurrens from the Turonian (Upper Cretaceous) of the Dalmatian region (southern Croatia) is documented here for the first time. The specimen represents the first articulated dentition of a ptychodontid shark that has been discovered from the Balkan Peninsula and the most complete ever found for the un-cuspidate species P. decurrens up to now. The reconstruction of the entire lower dentition of P. decurrens based on this exceptionally well-preserved dentition shows a wider crushing plate than previously hypothesised with bulgy teeth limited to the central area. Even though a defined cusp is missing, the occlusal surface of the teeth is undeniably raised and bulgy in some un-cuspidate species of Ptychodus (e.g., P. decurrens). This compels us to reconsider the use of terms such as high- and low-crowned as well as cuspidate and un-cuspidate. In addition, specimens previously assigned to dubious species (P. depressus, P. levis and P. oweni) or even varieties (P. polygyrus var. sulcatus and P. decurrens var. multiplicatus) are reassigned here to P. decurrens based on a careful comparison of the type materials. The reassessment of tooth root morphologies provides indicative traits for the identification of different genera of ptychodontid sharks (Paraptychodus and Ptychodus). The taxonomic revision presented here is crucial for securing a stable taxonomy and systematics of the shell-crushing shark P. decurrens, as well as of all ptychodontid sharks. The resulting updated taxonomy, together with the description and reconstruction of the new crushing plate, greatly contribute to a better understanding of one of the most enigmatic families (Ptychodontidae) of Mesozoic elasmobranchs. The detailed investigation of the new dentition of Ptychodus from Dalmatia is also a further step towards the discovery of Upper Cretaceous ichthyofaunas of one of the most palaeontologically important areas of the Balkan Peninsula.
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spelling doaj-art-675a02cb1ebb4f42a85353d65ed42e0f2025-01-12T12:38:11ZengSpringerOpenSwiss Journal of Palaeontology1664-23761664-23842025-01-01144112210.1186/s13358-024-00340-7New insights on the shell-crusher shark Ptychodus decurrens Agassiz, 1838 (Elasmobranchii, Ptychodontidae) based on the first known articulated dentition from the Upper Cretaceous of CroatiaManuel Amadori0Sanja Japundžić1Jacopo Amalfitano2Luca Giusberti3Eliana Fornaciari4Patrick L. Jambura5Jürgen Kriwet6Department of Palaeontology, Geozentrum, University of ViennaCroatian Natural History MuseumDipartimento Di Geoscienze, Università degli Studi di PadovaDipartimento Di Geoscienze, Università degli Studi di PadovaDipartimento Di Geoscienze, Università degli Studi di PadovaDepartment of Palaeontology, Geozentrum, University of ViennaDepartment of Palaeontology, Geozentrum, University of ViennaAbstract A new lower tooth plate of Ptychodus decurrens from the Turonian (Upper Cretaceous) of the Dalmatian region (southern Croatia) is documented here for the first time. The specimen represents the first articulated dentition of a ptychodontid shark that has been discovered from the Balkan Peninsula and the most complete ever found for the un-cuspidate species P. decurrens up to now. The reconstruction of the entire lower dentition of P. decurrens based on this exceptionally well-preserved dentition shows a wider crushing plate than previously hypothesised with bulgy teeth limited to the central area. Even though a defined cusp is missing, the occlusal surface of the teeth is undeniably raised and bulgy in some un-cuspidate species of Ptychodus (e.g., P. decurrens). This compels us to reconsider the use of terms such as high- and low-crowned as well as cuspidate and un-cuspidate. In addition, specimens previously assigned to dubious species (P. depressus, P. levis and P. oweni) or even varieties (P. polygyrus var. sulcatus and P. decurrens var. multiplicatus) are reassigned here to P. decurrens based on a careful comparison of the type materials. The reassessment of tooth root morphologies provides indicative traits for the identification of different genera of ptychodontid sharks (Paraptychodus and Ptychodus). The taxonomic revision presented here is crucial for securing a stable taxonomy and systematics of the shell-crushing shark P. decurrens, as well as of all ptychodontid sharks. The resulting updated taxonomy, together with the description and reconstruction of the new crushing plate, greatly contribute to a better understanding of one of the most enigmatic families (Ptychodontidae) of Mesozoic elasmobranchs. The detailed investigation of the new dentition of Ptychodus from Dalmatia is also a further step towards the discovery of Upper Cretaceous ichthyofaunas of one of the most palaeontologically important areas of the Balkan Peninsula.https://doi.org/10.1186/s13358-024-00340-7Tooth plateDurophagyLamniformesTaxonomyDalmatiaTuronian
spellingShingle Manuel Amadori
Sanja Japundžić
Jacopo Amalfitano
Luca Giusberti
Eliana Fornaciari
Patrick L. Jambura
Jürgen Kriwet
New insights on the shell-crusher shark Ptychodus decurrens Agassiz, 1838 (Elasmobranchii, Ptychodontidae) based on the first known articulated dentition from the Upper Cretaceous of Croatia
Swiss Journal of Palaeontology
Tooth plate
Durophagy
Lamniformes
Taxonomy
Dalmatia
Turonian
title New insights on the shell-crusher shark Ptychodus decurrens Agassiz, 1838 (Elasmobranchii, Ptychodontidae) based on the first known articulated dentition from the Upper Cretaceous of Croatia
title_full New insights on the shell-crusher shark Ptychodus decurrens Agassiz, 1838 (Elasmobranchii, Ptychodontidae) based on the first known articulated dentition from the Upper Cretaceous of Croatia
title_fullStr New insights on the shell-crusher shark Ptychodus decurrens Agassiz, 1838 (Elasmobranchii, Ptychodontidae) based on the first known articulated dentition from the Upper Cretaceous of Croatia
title_full_unstemmed New insights on the shell-crusher shark Ptychodus decurrens Agassiz, 1838 (Elasmobranchii, Ptychodontidae) based on the first known articulated dentition from the Upper Cretaceous of Croatia
title_short New insights on the shell-crusher shark Ptychodus decurrens Agassiz, 1838 (Elasmobranchii, Ptychodontidae) based on the first known articulated dentition from the Upper Cretaceous of Croatia
title_sort new insights on the shell crusher shark ptychodus decurrens agassiz 1838 elasmobranchii ptychodontidae based on the first known articulated dentition from the upper cretaceous of croatia
topic Tooth plate
Durophagy
Lamniformes
Taxonomy
Dalmatia
Turonian
url https://doi.org/10.1186/s13358-024-00340-7
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