Tag Archives: fossil

New fossils from Argentina

Just published: a paper by Miquel on continental gastropods from Argentina. “A new genus and two new fossil species of continental gastropods from the upper part of the Irene Formation—which is probably Huayquerian–Montehermosian (early Pliocene) and is exposed in the Quequén Salado River (Buenos Aires Province, Argentina)—are described: the new genus and species of freshwater gastropod Argentisioliella pardignasi (Cochliopidae) and a new species of landsnail of the family Bulimulidae (Bocourtia (Kuschelenia?) bonariensis). Argentisioliella pardignasi is morphologically related to those described for the Pebas Formation of Pliocene age. The specimens have bulloid morphology, long and narrow aperture, with a channeled peristome and two folds in the columellar wall. This is the first description of similar snails of the Pebas and Irene formations. Bocourtia (Kuschelenia?) bonariensis is the most ancient record for the genus, being recorded far away from the area of its current distribution (northwest Argentina). The specimen is an internal cast, with more than three convex whorls and a large aperture. Its distribution would coincide with the final phase of the Mio–Pliocene climatic change, when numerous terrestrial gastropods of Patagonian and Pampean provenance disappeared. A well-conserved specimen of the terrestrial snail Austroborus (Strophocheilidae Pilsbry), showing an almost complete shell, with more than 4.5 convex whorls, last whorl and large aperture, was also recorded. In the study area, this genus was present during the Pleistocene and Holocene, living in restricted areas of Argentina and Uruguay, with a disjunctive and relictual distribution“.

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Always interesting to see how palaeontologists are able to read those fragments. In this case the connection between Central Argentina and Pebas, in northeastern Peru on the Amazonian side, is remarkable. Thus a short but interesting paper.

Reference:
Miquel, S.E., 2019. A new genus and two new species of fossil continental gastropods from the early Pliocene of Argentina (Mollusca). – Ameghiniana 56 (2): 187–194.

Checklist of Pulmonate fossils

Just published by a group of 6 authors, Salvador et al. have made an annotated checklist of known Pulmonate gastropod fossils. In their own words “The South American fossil record of pulmonate gastropods counts with circa 100 species from the Cretaceous to the Pliocene. As this knowledge is largely scattered in the literature, we present here a checklist of these fossils, with relevant data about each species’ type locality, stratum and age, and illustrating the type specimens whenever possible. Moreover, some taxonomical problems are highlighted in the hope of garnering attention for future research”.

Fossils from the following families are treated: Chilinidae, Lymnaeidae, Planorbidae, Physidae, Achatinidae, Ferussaciidae, Charopidae, Punctidae, Cerionidae, Urocoptidae, Succineidae, Strophocheilidae, Bulimulidae, [Megaspiridae], Odontostomidae, Orthalicidae, Simpulopsidae, Gastrocoptidae, Pupillidae, Clausiliidae, and Xanthonychidae.

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A checklist like this is always a helpful instrument to bring knowledge together in one point, to highlight gaps and to make suggestions for future research.

Reference:
Salvador, R.B. et al., 2018. Annotated catalogue of the fossil Hygrophila and Eupulmonata (Mollusca: Gastropoda) from South America (Cretaceous – Neogene). – Neues Jahrbuch fuer Geologie und Palaeontologie Abhandlungen, 289 (3):249-280.

Amphibulima in Guadeloupe

In a paper recently published, Lenoble et al. report on fossil specimens of Amphibulima patula found on Guadeloupe and neighbouring islands.

Amphibulima patula (Bruguière, 1789) is a rare native terrestrial mollusc from Guadeloupe. The past distribution of this species, assessed by shells collected from archaeological sites, natural deposits or surface surveys, shows it previously had a wider distribution that extended across all the limestone islands of the Guadeloupe archipelago. Stratigraphical contexts and radiocarbon data suggest that the presence or abundance of A. patula is related to periods of wetter environmental or climatic conditions, indicating that environmental factors influenced past variations in the distribution of this species. Its limitation to rare ecological refuges in periods of dry climatic conditions, combined with human-induced landscape modifications, have led to significant reductions in the numbers of individuals of this species that is today threatened with extinction in the Guadeloupe Islands”.

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This is an interesting paper as it gives for the first time detailed radiocarbon data on this species, revealing the age of the fossils. The shells shown reveal an interesting variation. The paper contains also interesting information on ecological conditions and suggesting evidence for its former wider distribution.

Reference:
Lenoble, A. et al., 2018. Quartenary occurrence of the rare land snail Amphibulima patula (Bruguière, 1789) in Guadeloupe (Mollusca: Amphibulimidae): ecological and palaeoenvironmental implications. – Quartenaire, 29 (2): 121-130.

Fossil connections

Recently a review paper appeared by Hammouda et al. (2017), in which some links between northern Africa and South America are suggested. The abstract is as follows:

“Terrestrial gastropods occur in many North African localities in Eocene continental deposits. Here we analyse the faunal assemblage from the Hamada de Méridja Formation in southwestern Algeria, dated as Early to Middle Eocene on the basis of charophytes. The assem- blage consists of three closely related species that to date have been classified either in the extant Madagascan genus Leucotaenius v. Martens, 1860, or in the SW European Eocene genera Romanella Jodot, 1957 and Vicentinia Jodot, 1957. This is rejected for shell morphological and phylogeographical reasons, and a new classification as Maghrebiola gen. nov. is proposed. Maghrebiola is tentatively placed in the South American family Strophocheilidae, as species from the Early Eocene Itaboraí Basin of Brazil, currently placed in the genus Eoborus Klappenbach and Olazarri, 1970 in the family Strophocheilidae, superfamily Acavoidea, have a very similar shell habitus. This record possibly extends the known geographical range of the Strophocheilidae into the African continent during the Eocene. Immigration of this stock into North Africa during the Cretaceous via a still existing plate connection is assumed. An attribution of Maghrebiola to the African family Achatinidae is unlikely for shell morphological reasons despite certain habitus similarities, although the Priabonian genera Arabicolaria and Pacaudiella from Oman most likely belong into this family, and not to the Vidaliellidae as originally proposed. Possible causes for the very low diversity of the assemblage are mainly unfavourable living conditions, i.e. a relatively dry climate resulting in sparse vegetation and only occasional presence of water bodies, which may have had increased salinities, accounting for the lack of freshwater mollusks. The absence of any competing large gastropods may possibly have facilitated high intraspecific variability leading to sympatric occurrence of three closely related species, due to the animals occupying a wide range of available ecological niches. As the species discussed here have also been attributed to the genera Romanella and Vicentinia in the Vidaliellidae, we provide an appendix with annotated characterisations of most genera of the Vidaliellidae and list the nominal species assigned to them. This family is tentatively placed in the South American superfamily Orthalicoidea; its stock would have similarly immigrated from South America, but have successfully colonized mainly SW Europe, with only one Eocene species [Romanella kantarensis (Jodot, 1936)] recognized in Algeria”.

This paper presents a provoking view on the relations between northern Africa, soutwestern Europe and South America during the Eocene. Perhaps food for discussion among palaeontologists?

Reference:
Hammouda, S.A., Kadolsky, D., Adaci, M., Mebrouk, F., Bensalah, M., Mahboubi, M. & Tabuce, R., 2017. Taxonomic review of the ‘‘Bulimes’’, terrestrial gastropods from the continental Eocene of the Hamada de Méridja (northwestern Sahara, Algeria) (Mollusca: Stylommatophora: Strophocheilidae?), with a discussion of the genera of the family Vidaliellidae. – Paläontologische Zeitschrift, 91: 85-112.

New fossil Pupoides

Cabrera & Martinez (2017) have just published a paper on minute pupillids. “A new species of Pupoides Pfeiffer 1854, subgenus Ischnopupoides Pilsbry 1926, is described for the Late Cretaceous of Uruguay (Queguay Formation), being the oldest record of the genus and subgenus. Pupoides (I.) gnocco new species is characterized by a small dextral fusiform shell, constituted by a spire comprising five slightly convex whorls, oblicuous axial ornamentation, subrounded aperture, and an expanded outer lip that lacks dentition”.

Reference:
Cabrera, F. & Martinez, S., 2017. Late Cretaceous Pupoides Pfeiffer 1854 (Gastropoda: Pupillidae) from  Uruguay (Queguay Formation). – Journal of Conchology, 42 (5):333-338.

Did Neotropical snails occur in Africa and Europe?

Fossils allow us a peek into the past, and although a lot remains uncertain and sometimes highly speculative (no molecules but only shell morphology to start with), they offer sometimes challenging views on worlds that have gone.

What we now call the Neotropics possibly once had a wider extension, and a team of Algerian and European scientists have made a study of Algerian shells that possibly give a clue. Hammouda et al. (2017) present a review of Eocene “Bulimes” and reached interesting but still tentative results.

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Their abstract reads “Terrestrial gastropods occur in many North African localities in Eocene continental deposits. Here we analyse the faunal assemblage from the Hamada de Meridja Formation in southwestern Algeria, dated as Early to Middle Eocene on the basis of charophytes. The assemblage consists of three closely related species that to date have been classied either in the extant Madagascan genus Leucotaenius v. Martens, 1860, or in the SW European Eocene genera Romanella Jodot, 1957 and Vicentinia Jodot, 1957. This is rejected for shell morphological and phylogeographical reasons, and a new classication as Maghrebiola gen. nov. is proposed. Maghrebiola is tentatively placed in the South American family Strophocheilidae, as species from the Early Eocene Itaboraı Basin of Brazil, currently placed in the genus Eoborus Klappenbach and Olazarri, 1970 in the family Strophocheilidae, superfamily Acavoidea, have a very similar shell habitus. This record possibly extends the known geographical range of the Strophocheilidae into the African continent during the Eocene. Immigration of this stock into North Africa during the Cretaceous via a still existing plate connection is assumed. An attribution of Maghrebiola to the African family Achatinidae is unlikely for shell morphological reasons despite certain habitus similarities, although the Priabonian genera Arabicolaria and Pacaudiella from Oman most likely belong into this family, and not to the Vidaliellidae as originally proposed. Possible causes for the very low diversity of the assemblage are mainly unfavourable living conditions, i.e. a relatively dry climate resulting in sparse vegetation and only occasional presence of water bodies, which may have had increased salinities, accounting for the lack of freshwater mollusks. The absence of any competing large gastropods may possibly have facilitated high intraspecic variability leading to sympatric occurrence of three closely related species, due to the animals occupying a wide range of available ecological niches. As the species discussed here have also been attributed to the genera Romanella and Vicentinia in the Vidaliellidae, we provide an appendix with annotated characterisations of most genera of the Vidaliellidae and list the nominal species assigned to them. This family is tentatively placed in the South American superfamily Orthalicoidea; its stock would have similarly immigrated from South America, but have successfully colonized mainly SW Europe, with only one Eocene species [Romanella kantarensis (Jodot, 1936)] recognized in Algeria”.

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The most recent, total overview of fossil and Recent Gastropoda was by Zilch, who classified the genera Romanella and Vidaliella with others in the “?Familia Anadromidae” within the Bulimulacea [currently Orthalicoidea] (Zilch, 1960); these genera are now placed in a family on their own, but based on their morphology there might be a resemblance with the Megaspiridae (e.g. Thaumastus). The link between the Mediterranean area and South America is further shown in the presence of the Clausiliid Neniinae, which the authors use as one of their arguments for their grouping of Maghrebiola with the Strophocheilidae. All this is an interesting but not implausible hypothesis.

References:
Hammouda, S.A., Kadolsky, D., Adaci, M., Mebrouk, F., Bensalah, M., Mahbouhi, M. & Tabuce, R., 2017. Taxonomic review of the “Bulimes”, terrestrial gastropods from the continental Eocene of the Hamada de Méridja (northwestern Sahara, Algeria) (Mollusca: Stylommatophora: Strophocheilidae?), with a discussion of the genera of the family Vidaliellidae. — Paläontologische Zeitschrift, (advance online) doi:10.1007/s12542-016-0333-5
Zilch, A., 1960. Gastropoda 2. Euthyneura. In: Schindewolf, O. (ed.) Handbuch der Paläozoologie, 6 (3–4): 401–834. Berlin: Borntraeger.

 

New fossil land shells from Patagonia

Miquel & Rodriguez (2015 [2016]) published a new paper on fossil shells from Miocene deposits in Patagonia, Argentina. Among them four new species, of which one is placed in a new genus.

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“A remarkable fossil assemblage composed of five gastropod taxa is described from the Early Miocene of Santa Cruz (Patagonia, Argentina) in southernmost South America. The assemblage includes extinct and living genera South America, and on geographic distributions and represent background new information on spatial and across time distributions as well as identification of new taxa. A new taxon, Patagocharopa enigmatica n. gen. n. sp., is tentatively assigned to Charopidae. Gastrocopta patagonica n. sp. (Vertiginidae) represents the oldest record of Gastrocopta in Argentina and the southernmost record for the Americas. Punctum patagonicum n. sp. (Punctidae) represents the first record of Punctum for continental South America, and characterized by a protoconch with traces of axial costulae and a teleoconch with strong radial ribs. Zilchogyra miocenica n. sp. is the first Miocene record of the charopid genus Zilchogyra. Fragments of a possible Scolodonta (Scolodontidae) are recorded. Overall, the assemblage represents an important and useful paleoenvironmental tool. This fauna suggests that a more temperate and humid environment than today—with a more dense vegetation cover—was prevalent at this site during the Early Miocene”.

Although the paper appeared in the September 2015 issue of the Journal of Paleontology, the actual publication date seems 2016. In the PDF I received it says “Published online: 22 March 2016”, while also the copyright is from this year. As new taxa are introduced in this paper, this is relevant information.

Reference:
Miquel, S.E. & Rodriguez, P.E., 2015 [2016]. A novel late Early Miocene assemblage of terrestrial gastropods from Santa Cruz (Patagonia, Argentina). – Journal of Paleontology, 89(5): 748-761.