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A new species of Pseudhimalayites (Ammonitina, Aspidoceratoidea) from the Lower Tithonian of the Betic Range, Southern Spain

Parent Horacio, Ramos-Agustino Enrique, Scherzinger Armin, Schweigert Günter

Volumina Jurassica

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2023

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Vol. 21

19--26

EN

The Late Jurassic aspidoceratoid genus Pseudhimalayites Spath is scarcely recorded but widely distributed in the Andean basins, the Caribbean region, and in the European Tethys. From Ponti Zone (Lower Tithonian) rocks of the Betic Range in Carchelejo we describe here the new species Pseudhimalayites carchelejensis, based on a macroconch (female) holotype. The corresponding microconch (male), described from the same ammonite assemblage, would belong to the morphogenus Simocosmoceras Spath which groups the microconchs of Pseudhimalayites. P. carchelejensis n. sp. differs from the coeval Pseudhimalayites steinmanni (Haupt) by lacking ventral tubercles in the phragmocone and by bearing umbilical tubercles only from the adult whorl of the phragmocone. These differences illustrate a significant morphologic divergence between the Andean and the Tethyan lineages.

2

Ammonite assemblage and age of the hydrocarbon seep La Elina, Neuquén Basin, Argentina

Parent Horacio, Kaim Andrzej, Garrido Alberto C.

Annales Societatis Geologorum Poloniae

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2023

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Vol. 93, No. 4

353--361

EN

The ancient hydrocarbon seep deposits at the La Elina Ranch, Neuquén Basin, northern Patagonia, Argentina, are the only Mesozoic seep site in South America yielding metazoan fossils. Apart from benthic mollusc shells and worm tubes, they yielded a number of nektonic ammonoids. Four species of ammonoids were identified: Hildaitoides retrocostatus, Hammatoceras ex gr. insigne, Calliphylloceras cf. nilssoni, and Phylloceras sp. The occurrences of three species (H. ex gr. insigne, C. cf. nilssoni, and Phylloceras sp.) probably are fortuitous, while H. retrocostatus might have actually thrived in, or around the seep, as indicated by numerous well-preserved juveniles, in addition to some adult specimens. The bathymetric estimates indicate a depth not greater than 200 m, while the benthic molluscs, typical of hydrocarbon seeps, indicate a much greater depth. It is hypothesized that the deep-water taxa might have occurred in a shallower setting, owing to rising anoxia and/or strong input of continental waters from the eastern and/or southeastern deltaic system. The ammonite assemblage indicates that the seep at La Elina is (Andean) Middle Toarcian, probably Chilensis Zone, in age.

3

Aalenian (Jurassic) to Berriasian (Cretaceous) chronostratigraphic zonation and guide ammonites of the Central Andes (Argentina, Chile, Peru)

Parent Horacio

Volumina Jurassica

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2022

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Vol. 20

1--46

EN

In the Central Andes there are developed two marine basins with an extensive Jurassic record: the Neuquén (or Central Andean) Basin and the Tarapacá Basin. Their Jurassic and Lower Cretaceous ammonite successions have been studied extensively for more than 150 years, producing detailed chronostratigraphic scales based on ammonite zones and biohorizons. The ammonite faunas include Andean lineages, and cosmopolitan, Tethyan, Caribbean, North American, and Indo-Madagascan elements. This paper presents the results of a revision of the zonation of the interval Aalenian-Berriasian. Before presenting the results, this paper emphasizes the distinction between, and the convenient nomenclature for, biozones, zones, standard zones, and biohorizons. The scissum Hz. (new) is introduced in the lower (-most?) Manflasensis Zone (Aalenian). The Rotundum Subzone (new) with base at the cf.-leptus Hz., is introduced for the upper part of the Rotundum Zone (Bajocian). The Gulisanoi Zone (Bathonian) is standardized by designation of the cf.-aspidoides Hz. (new) as its base. The Chacaymelehuensis Zone (new) with base at the “prahecquense” Hz. (new) is introduced for the Callovian. The Cubanensis Zone (Oxfordian) is introduced to replace nominally, or to rename, the inconveniently named “Passendorferia” Zone. The Tarapacaense Zone (Oxfordian) is standardized by designation of the tarapacaense Hz. (new) as its base. The Tithonian Malarguensis Zone (formerly subzone) is here emended and standardized by designation of the malarguensis Hz. as its base; this zone replaces the unviable Mendozanus Zone. The Zitteli Zone is standardized by designation of the widely recorded perlaevis Hz. as its base. The Fascipartita Subzone (Internispinosum Zone) is standardized by designation of the internispinosum-beta Hz. (new) as its base. The Alternans Zone is standardized by designation of the vetustum Hz. as its base, and the Koeneni Zone (uppermost Tithonian) by designation of the striolatus Hz. as its base.

4

A review of the classification of Jurassic aspidoceratid ammonites – the Superfamily Aspidoceratoidea

Parent Horacio, Schweigert Günter, Scherzinger Armin

Volumina Jurassica

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2020

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Vol. 18, no. 1

47--52

EN

The aspidoceratid ammonites have been traditionally included in the superfamily Perisphinctoidea. However, the basis of this is unclear for they bear unique combinations of characters unknown in typical perisphinctoids: (1) the distinct laevaptychus, (2) stout shells with high growth rate of the whorl section area, (3) prominent ornamentation with tubercles, spines and strong growth lines running in parallel over strong ribs, (4) lack of constrictions, (5) short to very short bodychamber, and (6) sexual dimorphism characterized by miniaturized microconchs and small-sized macroconchs besides the larger ones, including changes of sex during ontogeny in many cases. Considering the uniqueness of these characters we propose herein to raise the family Aspidoceratidae to the rank of a superfamily Aspidoceratoidea, ranging from the earliest Late Callovian to the Early Berriasian Jacobi Zone. The new superfamily includes two families, Aspidoceratidae (Aspidoceratinae, Euaspidoceratinae, Epipeltoceratinae and Hybonoticeratinae), and Peltoceratidae (Peltoceratinae and Gregoryceratinae nov. subfam.). The highly differentiated features of the aspidoceratoids indicate that their life-histories were very different from those of the perisphinctoids; these ammonites show great promise for studies of developmental and evolutionary patterns and processes, and can be used for biostratigraphic-chronostratigraphic purposes and interprovincial correlations.

5

Pseudosonninia, a new genus of oppeliid ammonite (Haploceratoidea) from the Callovian (Middle Jurassic) of the Neuquén Basin, Argentina

Parent Horacio, Garrido Alberto C., Schweigert Günter, Brambilla Luciano

Volumina Jurassica

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2019

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Vol. 17, no. 1

39--48

EN

From the uppermost part of the Los Molles Formation (upper Lower and lower Middle Callovian) in Chacay Melehué (Neuquén Province, Argentina), a group of hecticoceratine ammonites with a conspicuous morphology not assimilable to any known genus of this subfamily has been recently discovered. These forms are inflated oxycones with a prominent, sharp keel developed from the juvenile phragmocone up to the adult peristome. The new genus Pseudosonninia is established on the basis of these ammonites, with Pseudosonninia chacaymelehuensis n. gen. n. sp. as its type species. The new genus seems to be endemic to the Neuquén Basin and is recorded here from the upper Lower and lower Middle Callovian of Chacay Melehué and Río de Los Patos.