Postcranial morphology of Aristonectes (Plesiosauria, Elasmosauridae) from the Upper Cretaceous of Patagonia and Antarctica

AbstractA partial, postcranial skeleton of a juvenile individual referred to Aristonectes cf. parvidens from the upper Maastrichtian López de Bertodano Formation, Isla Marambio (Seymour Island), Antarctica, is described. Additionally, two juvenile specimens, also referred to A. cf. parvidens from the Allen Formation (upper Campanian–lower Maastrichtian) and Jagüel Formation (upper Maastrichtian) (Río Negro province, Argentina), are redescribed. The analysis of the systematic value of the cervical centrum proportions of juvenile specimens of Elasmosauridae suggests that these elements can be used to differentiate juvenile specimens of A. cf. parvidens from juveniles of other Elasmosauridae. On this basis, the specimens described are referred to A. cf. parvidens. Based on the proportion of the cervical centra, the first South American plesiosaur described by Gay in 1848 is here referred to A. cf. parvidens. The coracoid of Aristonectes is described for the first time showing a cordiform fenestra, a feature only recorded in the Elasmosauridae among the Plesiosauria, therefore, these new data support the inclusion of Aristonectes within the Elasmosauridae. With the new material described in this paper, Aristonectes is one of the most frecuently recorded genera of Late Cretaceous plesiosaurs in the Southern Hemisphere.

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The oldest and first nearly complete skeleton of a chelid, of the Hydromedusa sub-group (Chelidae, Pleurodira), from the Upper Cretaceous of Patagonia

BSGF - Earth Sciences Bulletin ◽

10.2113/172.2.237 ◽

2001 ◽

Vol 172 (2) ◽

pp. 237-244 ◽

Cited By ~ 35

Author(s):

Marcelo de la Fuente ◽

France de Lapparent de Broin ◽

Teresa Manera de Bianco

Keyword(s):

Upper Cretaceous ◽

Cervical Vertebrae ◽

Lake Area ◽

Lower Eocene ◽

Rio Negro ◽

Caudal Vertebrae ◽

The Family ◽

Lower Maastrichtian ◽

Middle Member ◽

Upper Campanian

Abstract A new pleurodiran (side necked) turtle is described on material from the Upper Cretaceous of Patagonia, from sediments outcropping at Cerro Blanco, Yaminue Creek, Rio Negro, Argentina. The sediments are compared to those from the Pellegrini lake area referred to the middle Member of the Allen Formation, Upper Campanian-Lower Maastrichtian. Yaminuechelys gasparinii n.g., n.sp., is a pleurodiran turtle on the pelvis sutured to the shell and a chelid on the formula of cervical vertebrae and the lateral cheek emargination, deeply extended towards (as here) or up to the posterior emargination. It is the oldest record of a nearly complete skeleton of a chelid, long necked (elongated cervical vertebrae, lowered skull), and the first sufficiently known of the Chelodina-Hydromedusa group (elongated skull, lowered neural arch and centrum of the cervicals, low zygapophyses processes, strong polygoned decoration) and of the Hydromedusa sub-group (widened inner nares by reduced palatine ossification). The carapace is 41,8 cm long. It is more primitive than Hydromedusa (Eocene-Extant, South America) and retains primitive characters either still present or no more present in the other chelids of the Pseudemydura, Emydura and Phrynops groups (short necked) and Chelus group (long necked), representing the anterior clades of phyletic diversification [Gaffney, 1977], or evolutive grades, of the family. Such are plesiomorphic, relative to Hydromedusa, the less pronounced lateral skull emargination, wider and longer hyoid elements, wider nucal and cervical, this not drawn back, presence of lateral mesoplastra, not shortened bridge, straight borders of the not shortened and not widened posterior plastral lobe, amphicoelous sacrals and caudal vertebrae uniting amphicoelous, concavoplaty--(i.e. anteriorly concave, posteriorly flat) and procoelous or weakly procoelous elements. As Hydromedusa, Yaminuechelys n. g. retains primitive characters such as the long series of neurals, the very lateral attachment of the axillar and inguinal processes and the attachment of the pelvis, below pleural 8 (and 7 in the extant form) and a small part of the suprapygal, and the ischitatic sutures prolonged on the xiphiplastral points. It is distinguished by the apomorphic presence of a wide and week anterior carapacial notch. Yaminuechelys n.g., or aff. Yaminuechelys spp. are known in Patagonia by fragmentary remains in a dozen of Upper Cretaceous and two Palaeocene localities. Before them, chelids are known in the world only by undefined smaller forms from Lower Albian and Upper Albian-Cenomanian Patagonian localities. In Australia, they are known from Palaeocene-Lower Eocene (no Cretaceous data before) with already extant Australian diversified forms. Yaminuechelys n.g. demonstrates how long the diversification in chelids is realized in South Gondwana before the full break of the continents.

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Saldenioichthys remotus gen. et sp. nov. (Teleostei, Perciformes) and other acanthomorph remains from the Maastrichtian Saldeño Formation (Mendoza, Argentina)

Fossil Record ◽

10.5194/fr-6-161-2003 ◽

2003 ◽

Vol 6 (1) ◽

pp. 161-168

Author(s):

A. López-Arbarello ◽

G. Arratia ◽

M. A. Tunik

Keyword(s):

Upper Cretaceous ◽

Character Evolution ◽

Skeletal Remains ◽

Neural Spine ◽

New Taxon ◽

Postcranial Skeleton ◽

Caudal Skeleton ◽

Lower Maastrichtian ◽

Upper Campanian

Some isolated acanthomorph remains and a new taxon of perciform fishes, Saldenioichthys remotus gen. et sp. nov., from the Maastrichtian Saldeño Formation of Mendoza province, Argentina, are described and their systematic affinities are discussed. The new taxon is represented by a single incomplete, but well preserved postcranial skeleton. With the exception of a fully developed neural spine on the second preural centrum, it agrees with the generalized skeletal features of basal percoids, in particular the generalized perciform caudal skeleton. The only other Mesozoic perciform skeletal remains known so far are Nardoichthys, from the upper Campanian-lower Maastrichtian of Nardo (Italy) and Eoserranus from the Upper Cretaceous Lameta Formation (India). Therefore, the new perciform taxon from the Saldeño Formation represents one of the oldest members of this group, and due to its peculiar combination of primitive and derived characters, it raises several questions regarding character evolution on this lineage. Es werden einige isolierte Reste acanthomorpher Fische sowie ein neues Taxon der Perciformes, Saldenioichthys remotus gen. et sp. nov., aus dem Maastricht der Saldeño Formation in der Provinz Mendoza, Argentinien, werden beschrieben und ihre systematische Stellung wird diskutiert. Das neue Taxon ist durch ein einziges, unvollständiges, aber gut erhaltenes postkraniales Skelett repräsentiert. Mit Ausnahme eines vollstandig ausgebildeten Dornfortsatzes auf dem ersten präuralen Zentrum stimmt es mit der generalisierten Skelettmorphologie basaler Percoiden überein, insbesondere mit dem generalisierten perciformen Caudal-Skelett. Die einzigen anderen Skelettreste von Perciformen aus dem Mesozoikum sind Nardoichthys aus dem Ober-Campan/Unter-Maastricht von Nardo, Italien, und Eoserranus aus der Oberkreide der Lameta Formation, Indien, und die Gruppe ist ansonsten praktisch nur aus känozoischen Sedimenten bekannt. Somit stellt das neue Taxon aus der Saldeño Formation einen der ältesten Nachweise dieser Gruppe dar, und wirft aufgrund seiner ungewöhnlichen Kombination primitiver und fortschrittlicher Merkmale einige Fragen zur Merkmalsevolution in dieser Linie auf. doi:<a href="http://dx.doi.org/10.1002/mmng.20030060109" target="_blank">10.1002/mmng.20030060109</a>

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New late Cretaceous (Campanian and Maastrichtian) marine gastropods from California

Journal of Paleontology ◽

10.1017/s0022336000043419 ◽

2003 ◽

Vol 77 (1) ◽

pp. 50-63 ◽

Cited By ~ 3

Author(s):

Richard L. Squires ◽

Louella R. Saul

Keyword(s):

New Species ◽

Upper Cretaceous ◽

New Genus ◽

Middle Eocene ◽

First Record ◽

Northeastern Brazil ◽

Marine Gastropods ◽

The Pacific ◽

Lower Maastrichtian ◽

Upper Campanian

Three new genera and six new species of shallow-marine gastropods are named from Upper Cretaceous strata found mainly in California. The trochidsCidarina cretaceanew species andCidarina betanew species, the ficidBulbificopsis garzanew genus and new species, and the cancellariidMataxa aridanew species are from the Maastrichtian part of the Moreno Formation of north-central California. This is the earliest record ofCidarina, whose previous chronologic range was middle Eocene to Recent.Bulbificopsisis the first record of a Cretaceous ficid from the Pacific slope of North America, andMataxawas previously known only from Upper Cretaceous strata in the southeastern United States and northeastern Brazil. The buccinidEripachya jalamanew species and the fasciolariidCalkota daileyinew genus and new species are from the lower upper Campanian Jalama Formation in southern California.Calkotais also recognized herein as occurring in upper Maastrichtian strata of North Dakota and South Dakota. The new melongenid genus,Pentzia, established forFulgur hilgardiWhite, 1889, is from Campanian strata throughout California; middle Campanian strata on Sucia Island, Washington; and upper Campanian to lower Maastrichtian strata in northern Baja California, Mexico.

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NEOSELACHIANS FROM THE UPPER CAMPANIAN AND LOWER MAASTRICHTIAN (UPPER CRETACEOUS) OF THE SOUTHERN PYRENEES, NORTHERN SPAIN

Palaeontology ◽

10.1111/j.1475-4983.2007.00695.x ◽

2007 ◽

Vol 50 (5) ◽

pp. 1051-1071 ◽

Cited By ~ 20

Author(s):

JÜRGEN KRIWET ◽

RODRIGO SOLER-GIJÓN ◽

NIEVES LÓPEZ-MARTÍNEZ

Keyword(s):

Upper Cretaceous ◽

Northern Spain ◽

Lower Maastrichtian ◽

Upper Campanian

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Nannofossils, foraminifera and microforaminiferal linings in the Cenozoic diamictites of Cape Lamb, Vega Island, Antarctica

Polish Polar Research ◽

10.2478/popore-2014-0003 ◽

2014 ◽

Vol 35 (1) ◽

pp. 1-26 ◽

Cited By ~ 6

Author(s):

Andrea Concheyro ◽

Andrea Caramés ◽

Cecilia R. Amenábar ◽

Marina Lescano

Keyword(s):

Early Cretaceous ◽

Late Cretaceous ◽

First Record ◽

Organic Layer ◽

Sediment Sources ◽

Lower Maastrichtian ◽

James Ross Island ◽

The Antarctic ◽

Upper Maastrichtian ◽

Upper Campanian

AbstractMicropaleontological and palynological samples from three Cenozoic diamictites at Cape Lamb, Vega Island, James Ross Basin were analysed. Fossiliferous samples yielded reworked and autochthonous assemblages of Mesozoic calcareous nanno− fossils, impoverished Cretaceous foraminifera together with Neogene species, as well as Late Cretaceous dinoflagellate cysts, pollen, spores and abundant Cenozoic micro− foraminiferal linings. The recovered nannoflora indicates Early Cretaceous (Hauteri− vian-Albian) and Late Cretaceous (Santonian-Early Campanian) ages, suggesting an in− tensive reworking of marine sediments. The presence of the Early Cretaceous species Nannoconus circularis Deres et Acheriteguy in the diamictite represents its first record for the James Ross Basin. The scarce foraminiferal fauna includes Pullenia jarvisi Cushman, which indicates reworking from lower Maastrichtian-lower Paleocene sediments, and also the Neogene autochthonous Trochammina sp. aff. T. intermedia. The in− ner−organic layer observed inside this specimen appears to be identical to microfora− miniferal linings recovered from the same sample. Palynomorphs found in the studied samples suggest erosion from the underlying Snow Hill Island and the Lopez de Bertodano Formation beds (upper Campanian-upper Maastrichtian). These recovered assemblages indicate either different periods of deposition or reworking from diverse sources during Cenozoic glaciation, originating in James Ross Island and the Antarctic Peninsula with the influence of local sediment sources.

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Calcareous nannofossils from the upper Campanian–Maastrichtian (Upper Cretaceous) in the Kladorub Formation (Kula tectonic zone, NW Bulgaria)

Geologica Balcanica ◽

10.52321/geolbalc.48.1.73 ◽

2019 ◽

Vol 48 (1) ◽

pp. 73-101

Author(s):

Georgi Granchovski

Keyword(s):

Upper Cretaceous ◽

Calcareous Nannofossils ◽

Tectonic Zone ◽

Lower Upper ◽

Upper Maastrichtian ◽

Stratigraphic Interval ◽

Upper Campanian

A detailed investigation into the calcareous nannofossils from the upper Campanian–Maastrichtian deposits of the Kladorub Formation (NW Bulgaria) has been carried out in order to examine their taxonomic content and test the applicability of cosmopolitan zonation schemes for this stratigraphic interval in the country. The Kladorub Formation is composed of silty to fine-sandy marlstones and rare marly limestones, occasionally interbedded with sandstone layers. The recovered nannofloras are abundant, taxonomically diverse and exhibit predominantly moderate preservation, which allowed precise taxonomic identifications and biostratigraphic analysis to be made. As a result, the presence of two previously undocumented, biostratigraphically significant taxa has been recorded (i.e., Eiffellithus parallelus and Ceratolithoides kamptneri). Consequently, the studied Upper Cretaceous sediments have been assigned to subzone UC15dTP (pars.)–subzone UC20dTP; in the uppermost 2 m of the section, the presence of zone NP1 has also been indicated, which is in concordance with previous authors’ data. Due to the lack of proper chronostratigraphic framework for the Kladorub Formation, top Uniplanarius trifidus and base Lithraphidites quadratus have, respectively, been used to approximate the Campanian/Maastrichtian and lower/upper Maastrichtian boundaries. The Cretaceous/Palaeogene boundary, however, could not be drawn with precision, because it falls within a 6.5-m interval of non-exposure. The resulting biostratigraphic framework offers higher stratigraphic resolution than previously used local zonation schemes and allows correlation with coeval sedimentary successions from other parts of the Tethyan and Boreal realms.

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New material of “Eurysternidae” (Thalassochelydia, Pan-Cryptodira) from the Kimmeridgian of the Swiss Jura Mountains

10.31233/osf.io/4g3pq ◽

2019 ◽

Author(s):

Christian Püntener ◽

Jérémy Anquetin ◽

Jean-Paul Billon-Bruyat

Keyword(s):

New Species ◽

Late Jurassic ◽

Jura Mountains ◽

Marine Turtles ◽

Coastal Marine ◽

Juvenile Individual ◽

New Material ◽

Swiss Jura ◽

First Time

The region of Porrentruy (Swiss Jura Mountains) is known for its rich and diverse assemblage of Late Jurassic coastal marine turtles (Thalassochelydia). Dominated by the “Plesiochelyidae”, this assemblage also includes representatives of the two other thalassochelydian groups, the “Thalassemydidae” and “Eurysternidae.” In this study, we present new shell-based material from Porrentruy referable to eurysternids. One specimen represents a juvenile individual or a relatively small taxon, and is notably characterized by a well fenestrated plastron exhibiting a wider than long central plastral fontanelle. Two other specimens are much larger and possibly represent the largest eurysternids known to date. The fourth specimen is characterized by a unique plastral morphology otherwise only known in very small juveniles. This is the first time this unique plastral morphology is known to persist in an adult or subadult. The new material described herein represents at least three distinct taxa, all of them probably new. However, we refrain from naming new species based on this incomplete material in order to avoid adding confusion to an already complex taxonomical situation. This study provides new insights into the great diversity of eurysternids during the Late Jurassic.

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Exquisite air sac histological traces in a hyperpneumatized nanoid sauropod dinosaur from South America

Scientific Reports ◽

10.1038/s41598-021-03689-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Tito Aureliano ◽

Aline M. Ghilardi ◽

Bruno A. Navarro ◽

Marcelo A. Fernandes ◽

Fresia Ricardi-Branco ◽

...

Keyword(s):

Computed Tomography ◽

South America ◽

Ct Scan ◽

Upper Cretaceous ◽

Postcranial Skeleton ◽

Air Sacs ◽

Neural Canal ◽

Scan Data ◽

Pneumatic Structures ◽

First Time

AbstractThis study reports the occurrence of pneumosteum (osteohistological structure related to an avian-like air sac system) in a nanoid (5.7-m-long) saltasaurid titanosaur from Upper Cretaceous Brazil. We corroborate the hypothesis of the presence of an air sac system in titanosaurians based upon vertebral features identified through external observation and computed tomography. This is the fifth non-avian dinosaur taxon in which histological traces of air sacs have been found. We provided a detailed description of pneumatic structures from external osteology and CT scan data as a parameter for comparison with other taxa. The camellate pattern found in the vertebral centrum (ce) of this taxon and other titanosaurs shows distinct architectures. This might indicate whether cervical or lung diverticula pneumatized different elements. A cotylar internal plate of bone tissue sustains radial camellae (rad) in a condition similar to Alamosaurus and Saltasaurus. Moreover, circumferential chambers (cc) near the cotyle might be an example of convergence between diplodocoids and titanosaurs. Finally, we also register for the first time pneumatic foramina (fo) and fossae connecting camellate structures inside the neural canal in Titanosauria and the second published case in non-avian dinosaurs. The extreme pneumaticity observed in this nanoid titanosaur contrasts with previous assumptions that this feature correlates with the evolution of gigantic sizes in sauropodomorphs. This study reinforces that even small-bodied sauropod clades could present a hyperpneumatized postcranial skeleton, a character inherited from their large-bodied ancestors.

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Exceptionally well-preserved silicified hippuritid rudist bivalves from the lower Maastrichtian of Puerto Rico

Carnets de géologie (Notebooks on geology) ◽

10.2110/carnets.2020.2018 ◽

2020 ◽

Vol 20 (18) ◽

pp. 333-366

Author(s):

Simon F. Mitchell

Keyword(s):

Puerto Rico ◽

New World ◽

Three Dimensional ◽

Acid Digestion ◽

Distinctive Morphology ◽

New Material ◽

Lower Maastrichtian ◽

Rudist Bivalves ◽

Left And Right ◽

First Time

Exceptionally well-preserved (silicified) hippuritid rudists occur in the El Rayo Formation (lower Maastrichtian) of south-western Puerto Rico. Three species belonging to three different genera are present: Caribbea muellerreidi (VERMUNT), Laluzia peruviana (GERTH) and Parastroma guitarti (PALMER). Acid digestion of the limestones has resulted in a collection with numerous three-dimensional left and right valves many with the preservation of the minute details of the pore system. The morphological features of each species are described, and many features are illustrated for the first time. The new material, coupled with descriptions from other studies, demonstrates that six genera of endemic hippuritids evolved in two separate radiations in the New World: an older radiation of forms that had pallial canals in their left valves (Barrettia, Whitfieldiella and Parastroma) and a younger radiation of forms lacking pallial canals in their left valves (Laluzia, Caribbea and Praebarrettia). The exquisite preservation also reveals that in these endemic New World hippuritids the sockets for the teeth consisted of slots into which ribs on the teeth fitted; this contrasts with Old World hippuritids that have true sockets formed from upfolds of the tabulae for the teeth. The distinctive morphology of the tooth sockets is here used to define a monophyletic subfamily for which the name Barrettiinae CHUBB is available.

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Shallow-marine serpentinization-derived fluid seepage in the Upper Cretaceous Qahlah Formation, United Arab Emirates

Geological Magazine ◽

10.1017/s0016756821000121 ◽

2021 ◽

pp. 1-11

Author(s):

Benjamin Eickmann ◽

Crispin T. S. Little ◽

Jörn Peckmann ◽

Paul D. Taylor ◽

Adrian J. Boyce ◽

...

Keyword(s):

United Arab Emirates ◽

Upper Cretaceous ◽

Rock Interaction ◽

Cemented Sand ◽

Shallow Marine ◽

Fluid Seepage ◽

Lower Maastrichtian ◽

Calcite Cement ◽

Semail Ophiolite ◽

Upper Campanian

Abstract Serpentinization of ultramafic rocks in the sea and on land leads to the generation of alkaline fluids rich in molecular hydrogen (H2) and methane (CH4) that favour the formation of carbonate mineralization, such as veins in the sub-seafloor, seafloor carbonate chimneys and terrestrial hyperalkaline spring deposits. Examples of this type of seawater–rock interaction and the formation of serpentinization-derived carbonates in a shallow-marine environment are scarce, and almost entirely lacking in the geological record. Here we present evidence for serpentinization-induced fluid seepage in shallow-marine sedimentary rocks from the Upper Cretaceous (upper Campanian to lower Maastrichtian) Qahlah Formation at Jebel Huwayyah, United Arab Emirates. The research object is a metre-scale structure (the Jebel Huwayyah Mound) formed of calcite-cemented sand grains, which formed a positive seafloor feature. The Jebel Huwayyah Mound contains numerous vertically orientated fluid conduits containing two main phases of calcite cement. We use C and O stable isotopes and elemental composition to reconstruct the fluids from which these cements precipitated and infer that the fluids consisted of variable mixtures of seawater and fluids derived from serpentinization of the underlying Semail Ophiolite. Based on their negative δ13C values, hardgrounds in the same section as the Jebel Huwayyah Mound may also have had a similar origin. The Jebel Huwayyah Mound shows that serpentinization of the Semail Ophiolite by seawater occurred very soon after obduction and marine transgression, a process that continued through to the Miocene, and, with interaction of meteoric water, up to the present day.

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