Tag Archives: fossil

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.

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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.

A new fossil Radiodiscus

Papers on Neotropical fossils are rare, but Sergio Miquel is a regular contributor of them. Although Turazzini & Miquel (2014) was overlooked by me, I mention the paper now it came to my attention. The abstract follows after the break.

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“Numerous fossil gastropods have been recorded in an edaphic level of the middle section of the the Aisol Formation (Mendoza Province, Argentina). This stratigraphic section bears an association of fossil mammals suggesting an early Pliocene age (possible Montehermosan SALMA). Up to four taxa of gastropods have been identified, belonging in Succinea Draparnaud (Succineidae), Gastrocopta Wollaston (Vertiginidae), Bostryx Troschel (Bulimulidae), and a new species of Radiodiscus Pilsbry and Ferriss (Charopidae). The fossil record of terrestrial pulmonate mollusks in Argentina is scarce and mainly restricted to the Quaternary. Thus, the record of these taxa is of paramount importance because it constitutes the oldest record of Gastrocopta and Succinea in Argentina, the first record of Bostryx in Mendoza Province, and the first record of the family Charopidae (Radiodiscus sanrafaelensis nov. sp.) in Pliocene deposits of Argentina”.

Reference:
Turazzini, G.F. & Miquel, S.E., 2014. A terrestrial gastropod community from the Early Pliocene (Neogene) of Mendoza, Argentina, with description of a new species of Radiodiscus Pilsbry and Ferriss, 1906 (Mollusca: Pulmonata: Charopidae). – Ameghiniana, 51(5): 396-404.

New fossil species from Argentina

Miquel & Rodriguez (2016) describe a fossil fauna found in southern Patagania with an interesting composition. One new genus and four new species are described.

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The abstract is: “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”.

MiquelRodriguez7

Reference:
Miquel, S.E. & Rodriguez, P.E., 2016. A novel late Early Miocene assemblage of terrestrial gastropods from Santa Cruz (Patagonia, Argentina). — Journal of Paleontology X: 1–14 (advance access).

New fossil Cerion from Cuba

Fossil Cerionidae are getting more attention, with the recent paper of Harasewych on this subject. Suarez Torres (2015) has now described a new fossil Cerion species from eastern Cuba. The abstract of this paper in Spanish reads: “Cerion petreus sp. nov. is described on fossil state, with type locality at El Guanal, Punta de Maisí, Guantánamo province. This finding allows us to report the occurrence of this genus in Eastern Cuba since Pliocene to Lower Pleistocene”.

Suarez2015

So far, only two fossil species were known. The discovery of this third species is thus a nice addition to our knowledge of this family, which is represented with more than 100 Recent taxa on this island.

Reference:
Suarez Torres, A., 2015. Nueva especie fósil de Cerion Röding, 1798 (Mollusca: Pulmonata: Cerionidae) de Cuba Oriental. – Novitates Caribaea 8: 120–127.