Remarks on the Species Concept in Paleontology

Drooger, C. W.

doi:10.2307/1483957

Cited by 4 publications

(3 citation statements)

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“…In zoology, species are natural units defined on reproductive barriers to gene flow, notwithstanding operational challenges for their delineation. In palaeontology, addition of the time factor requires limits that are subjective and more or less arbitrary, and in any case different from the limits in zoology (Drooger 1954). Vertebrate palaeontology typically works with one or a very few specimens and so is unable to assess characters against a backdrop of inter-individual variation within species.…”

Section: Discussionmentioning

confidence: 99%

The Australian gulf snapping turtle Elseya lavarackorum (Testudines: Chelidae) revisited—Is the late Pleistocene fossil species extant?

Thomson¹,

Friol²,

White³

et al. 2023

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Disagreement exists on the taxonomic identity of the extant populations of the Australian Elseya referred to in 1992 as the gulf Elseya (= Elseya sp. aff. dentata [Nicholson]). The extant form has since 1997 been considered conspecific with the late Pleistocene fossil Elseya lavarackorum (White and Archer, 1994). Recently it has been considered a new species, Elseya oneirosJoseph-Ouni et al., 2020, conspecific with another fossil found in the same site and stratum as Elseya lavarackorum. Here we re-examine the fossil material and reassess the characters used by previous authors in an attempt to decide the issue. We find that the anterior bridge suture with the carapace of the fossil Elseya lavarackorum is associated with extensive and prominent plastral elements, which has led to misinterpretation of characters associated with this structure. We furthermore show that interindividual variation in sulci patterns is so great as to render them of little taxonomic value. On the basis of (a) deviation of the anterior shape of the carapace from ovoid such that, in aged individuals, the most anterior point of the carapace occurs at marginal scutes M2 (a resultant nuchal bay occurs in such individuals); (b) the typical absence of a cervical scute; (c) no evidence of a medial constriction in the anterior bridge strut suture; and (d) absence of evidence of any other informative variation of taxonomic value; we conclude that the decision to consider the late Pleistocene (ca 23 kyr old) fossil and the extant Elseya sp. aff. dentata [Nicholson] as Elseya lavarackorum (White and Archer, 1994) as conspecific should stand.

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Section: Discussionmentioning

confidence: 99%

The Australian gulf snapping turtle Elseya lavarackorum (Testudines: Chelidae) revisited—Is the late Pleistocene fossil species extant?

Thomson¹,

Friol²,

White³

et al. 2023

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“…In this context, the validity of subspecies as taxonomic entities lies in the concept of geographical variation (i.e. the organization of morphological variation following a geographical pattern; Wilson and Brown ; Drooger ; Mayr ; Thorpe ; Mallet ). Otherwise, subspecies become just arbitrary sections in a continuum of variation.…”

Section: The Genus Ptychomya In the Lower Cretaceous Of Argentinamentioning

confidence: 99%

Giving taxonomic significance to morphological variability in the bivalve Ptychomya Agassiz

2015

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The taxonomic significance of the morphological variability present in the genus Ptychomya Agassiz has remained obscure due to inadequacy of the traditional qualitative approach to account for complex patterns of variation. In this work, we focus on solving the distinction between intra-and interspecific variability in Ptychomya from Hauterivian marine beds of the Neuqu en Basin (west-central Argentina), a longstanding and unresolved palaeontological issue, using the quantitative framework provided by geometric morphometrics and multivariate statistics. The species Ptychomya koeneni Behrendsen and several subspecies had been recognized in the studied succession by former authors based on qualitative morphological descriptions. We tested two hypotheses: (1) that there exist morphological discontinuities between hypothesized species that mark their bound-aries; and (2) that morphology follows a pattern of geographical variation, suitable for recognition of subspecies. We find two morphological groups in the studied sample, with a significant morphological gap between them, supporting the idea that there are at least two species in the studied succession, Ptychomya cf. koeneni and Ptychomya coihuicoensis Weaver. On the other hand, we found no correspondence between morphological and geographical distributions, leading to the conclusion that the named subspecies are invalid taxa. This study highlights the potential of this methodological approach for solving the taxonomy of this notorious genus of pandemic distribution during the Cretaceous.

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“…Le terme « sous-esp£ce », dont on a tant fait usage ces dernieres annees, suppose ma inte s fois un meme type d'isolemcnt, mais avec une signification plus « Ipurde ». Je suis d'accord avec Drooger (1954) ä propos du terme « varidt4 » ; bien qu'il ne soit pas officiellement reconnu en taxinomie, il peut souvent donner une possibilito ideale d'evitement quand il est question de points fixes dans une longue serie, montrant une variabilite restreinte ou grande. Aussi, dans-le cas present de la « race » blesense, prc^rerais-je le terme « variete » « subspecies ».…”

Section: Comparaisons Avec D'autres Espicesunclassified

Un Nouvel Anchitherium Découvert en Hollande Comme Fossile Erratique

Erdbrink¹

1959

Mammalia

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Une decouverte exceptionnelle, la demi-mandibule gauche d'un Anchitherium primitif, fut faitc par un amateur de geologic hollandais dans une sablierc dans la partie nord des Pays-Bas. II s'agit ici non seulement (Tun rare erratique, empörte, soit par la nappe de glace pleistocone (rissienne), soit par les eaux des rivieres prerissiennes, d'un gisement tertiaire en Allemagne, mais aussi d'une espece nouvelle importante pour revolution et la position stratigraphique du genre en Europe. Dans la presente publication, cette decouverte est decrite et comparee avcc les autres especes primitives connues d'Europe et d'Amerique du Nord. ClRCONSTANCES DE LA DICOUVERTEA la fin du mois de Janvier 1955, un amateur hollandais, M. E. Zuurdeeg, d'Ede, recueillit un curieux fragment de mandibule fossile contenant des dents qui indiquaient Pexistence d'une affinite entre cette piece et le genus Anchitherium, un Equide primitif. Cette trouvaille fut faite lors d'une excursion aux sablieres situees pres du hameau de Garderen, dans la region du Veluwe. Une grande piece de corail fossilisee etait simultanement ramassee dans la meme sabliere.Le Veluwe est une region sableuse et relativement elevee dans la partie septentrionale des Pays-Bas. Les sediments qu'on y rencontre peuvent etre dates ; ils sont, pour la plupart, anterieurs ä la grande glaciation penultieme (appelee, dans la geologic quaternaire alpine, glaciation Riss). Ces sediments ont ete partiellement pousses et petris par la nappe de glace descendue de Scandi-Brought to you by |

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Remarks on the Species Concept in Paleontology

Cited by 4 publications

References 0 publications

The Australian gulf snapping turtle Elseya lavarackorum (Testudines: Chelidae) revisited—Is the late Pleistocene fossil species extant?

The Australian gulf snapping turtle Elseya lavarackorum (Testudines: Chelidae) revisited—Is the late Pleistocene fossil species extant?

Giving taxonomic significance to morphological variability in the bivalve Ptychomya Agassiz

Un Nouvel Anchitherium Découvert en Hollande Comme Fossile Erratique

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