A palynological investigation of plesiosaur-bearing rocks from the Upper Cretaceous Tahora Formation,Mangahouanga, New Zealand

High-palaeolatitude plesiosaur, mosasaur and, more rarely, dinosaur fossils are well known from the Maungataniwha Sandstone Member of the Tahora Formation in Mangahouanga Stream, Hawkes Bay, New Zealand. A palynological investigation of strata exposed along Mangahouanga Stream and of transported boulders hosting vertebrate fossils reveals well-preserved assemblages dominated by terrestrial pollen and spores but also including marine dinoflagellate cysts in some samples. The palynofacies are strongly dominated by wood fragments including charcoal; one outcrop sample and the sample taken from a boulder hosting plesiosaur vertebrae contain entirely terrestrially derived palynoassemblages, suggesting a freshwater habitat for at least some of the plesiosaurs. The host unit spans the Santonian to lowermost Maastrichtian, while the key pollen taxa Nothofagidites senectus and Tricolpites lilliei, together with the dinocyst Isabelidinium pellucidum and the megaspore Grapnelispora evansii, indicate a late Campanian to early Maastrichtian age for the fossiliferous boulders. The palynoflora indicates a mixed local vegetation dominated by podocarp conifers and angiosperms with a significant tree-fern subcanopy. The presence of taxa with modern temperate distributions, such as Nothofagus (southern beech), Proteaceae and Cyatheaceae (tree-ferns), indicates a mild-temperate climate and lack of severe winter freezing during the latest Cretaceous, providing an ecosystem that most probably made it possible for polar dinosaurs to overwinter in this part of the world.     

First record of Carinodens (Squamata,Mosasauridae) from the uppermost Maastrichtian of Stevns Klint,Denmark

Milàn, J., Jagt, J.W.M., Lindgren, J. & Schulp, A.S., November 2017. First record of Carinodens (Squamata, Mosasauridae) from the uppermost Maastrichtian of Stevns Klint, Denmark. Alcheringa 42, 597-602. ISSN 0311-5518.

Here we report on an important addition to the Late Cretaceous fossil record of marine reptiles from Denmark: a tooth crown of the rare durophagous mosasaur Carinodens minalmamar found in the uppermost Maastrichtian strata at the UNESCO World Heritage Site Stevns Klint. The tooth was found within the uppermost few metres of the Maastrichtian chalk placing it within the latest 50.000 years prior to the K/Pg boundary. The new find is a shed crown probably representing a tooth from the 11th to 13th position in the jaw. The tooth represents the northernmost occurrence of the genus Carinodens. Previous mosasaur finds from Denmark have all been from the hypercarnivorous mosasaurids Mosasaurus hoffmannii and Plioplatecarpus sp., thus our specimen adds a new trophic niche exploited by marine tetrapods in the food web of the latest Maastrichtian of Denmark.

Jesper Milàn* [jesperm@oesm.dk], Geomuseum Faxe/Østsjællands Museum, Østervej 2, 4640 Faxe, Denmark; John W.M. Jagt [john.jagt@maastricht.nl], Natuurhistorisch Museum Maastricht, De Bosquetplein 6–7, 6211 kJ Maastricht, the Netherlands; Johan Lindgren [johan.lindgren@geol.lu.se], Department of Geology, Lund University, Sölvegatan 12, 223 62 Lund, Sweden. Anne S. Schulp? [anne.schulp@naturalis.nl], Natuurhistorisch Museum Maastricht, De Bosquetplein 6–7, 6211 kJ Maastricht, the Netherlands. *Also affiliated with: Natural History Museum of Denmark, Øster Voldgade 5–7, 1465 Copenhagen K, Denmark. ?Also affiliated with: Naturalis Biodiversity Center, Darwinweg 2, 2333 CR Leiden, the Netherlands, and Faculteit Bètawetenschappen, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, the Netherlands.     

A new elasmosaurid specimen from the upper Maastrichtian of Antarctica: new evidence of a monophyletic group of Weddellian elasmosaurids

O’Gorman, J.P. & Coria, R.A. September 2016. A new elasmosaurid specimen from the upper Maastrichtian of Antarctica: new evidence of a monophyletic group of Weddellian elasmosaurids. Alcheringa 41, xxx–xxx. ISSN 0311-5518

A new fossil elasmosaurid specimen, MLP 15-I-7-48, from the upper Maastrichtian Sandwich Bluff Member of the López de Bertodano Formation, Vega Island, Archipelago James Ross, Antarctica, is described. The fossil is a well-preserved anterior limb, which shares with Vegasaurus molyi from the upper Maastrichtian of Antarctica, a concave to flat anterior margin of the humeral shaft, and with Vegasaurus molyi and Aphrosaurus furlongi from the upper Maastrichtian of California, a well-defined depression on the anterior margin of the ventral surface of the humeral shaft. A phylogenetic analysis recovered MLP 15-I-7–48 as sister group of the lower Maastrichtian Vegasaurus molyi within a new clade nominated as Weddellonectia: Kawanectes lafquenianum ((Vegasaurus molyi; MLP 15-I-7–48) (Morenosaurus stocki (Aristonectinae))). This indicates that the previously proposed faunal turnover between the early and late Maastrichtian Weddellian marine reptile fauna, did not severely affect the non-aristonectine elasmosaurids. Additionally, other taxa previously considered evidence of a faunal turnover are re-evaluated.

José P. O’Gorman. [joseogorman@fcnym.unlp.edu.ar]. División Paleontología Vertebrados, Museo de La Plata, Universidad Nacional de La Plata, Paseo del Bosque s/n., B1900FWA, La Plata, Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina. Rodolfo A. Coria. [rcoria@unrn.edu.ar]. Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro—Subsecretaría de Cultura de Neuquén—Museo Carmen Funes, Av. CVórdoba 55 (8318), Plaza Huincul, Neuquén, Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina.     

New species of organic-walled dinoflagellate cysts from the Maastrichtian–Danian boundary interval at Ouled Haddou,northern Morocco

Slimani, H., Louwye, S. & Toufiq, A., September 2012. New species of organic-walled dinoflagellate cysts from the Maastrichtian–Danian boundary interval at Ouled Haddou, northern Morocco. Alcheringa 36, 341–358. ISSN 0311-5518.

Seven new dinoflagellate cyst species and subspecies, previously figured under open nomenclature, from Maastrichtian and Danian deposits of Ouled Haddou (eastern external Rif Chain) in northern Morocco are formally described, and their stratigraphic ranges are clarified. Conosphaeridium lifum sp. nov. and Kenleyia chabaka sp. nov. have fibrous and reticulate wall surfaces, respectively. Oligosphaeridium saghirum sp. nov. is a small cyst with funnel-shaped distal process extremities. Spiniferella cornuta subsp. kacira subsp. nov. and Fibrocysta brevispinosa sp. nov. are distinguishable by their very short processes. Riculacysta chaouka sp. nov. is characterized by its perforate spinose ectophragm. Andalusiella bacita sp. nov. is a small and spindle-shaped cyst with only a single antapical horn.     

Ammonite dating of latest Cretaceous mosasaurid reptiles (Squamata,Mosasauroidea) from Jordan—preliminary observations

Jagt, J.W.M., Jagt-Yazykova, E.A., Kaddumi, H.F. & Lindgren, J., April 2017. Ammonite dating of latest Cretaceous mosasaurid reptiles (Squamata, Mosasauroidea) from Jordan—preliminary observations. Alcheringa 42, 587-596. ISSN 0311-5518

Newly collected ammonoid material from the uppermost Cretaceous portion of the Muwaqqar Chalk Marl Formation exposed some 30 km southeast of the Qasr Al’Harrana area (east-central Jordan) includes medium-sized baculitids (Baculites ovatus auctorum, non Say), the sphenodiscid Libycoceras acutodorsatus (Noetling) and the pachydiscids Menuites fresvillensis (Seunes) and Pachydiscus (Pachydiscus) dossantosi (Maury). Of the two last named taxa, the former is a good marker species for the upper Maastrichtian, with records from Europe, central Chile, South India, Baluchistan (Pakistan), Australia, Madagascar and South Africa. The latter is known from the United Arab Emirates/Oman border area, from strata of (late) early to early late Maastrichtian age, as well as from more poorly constrained Maastrichtian levels in Brazil and Nigeria. A comparison with ammonoid assemblages from the Maastrichtian type area (southeast Netherlands/northeast Belgium) suggests correlation of the Muwaqqar Chalk Marl Formation with the middle/upper Maastricht Formation (Emael and Nekum members, ca 66.5–66.1 Ma) and the upper part of the coeval Kunrade Formation. However, associated ‘tegulated’ inoceramids of the Tenuipteria argentea group from the Muwaqqar Chalk Marl Formation favour equivalence with a higher level of the Maastrichtian type area, i.e., the Meerssen Member. From the upper Maastricht Formation and the equivalent upper part of the Kunrade Formation, the following mosasaur genera are currently known: Mosasaurus, Prognathodon, Plioplatecarpus and Carinodens. Interestingly, coeval strata of the Muwaqqar Chalk Marl Formation in east-central Jordan have yielded remains of a largely comparable suite comprising Prognathodon, Mosasaurus, Carinodens and an unnamed, highly derived plioplatecarpine.

John W.M. Jagt* [john.jagt@maastricht.nl], Natuurhistorisch Museum Maastricht, de Bosquetplein 6–7, 6211 kJ Maastricht, the Netherlands; Elena A. Jagt-Yazykova [eyazykova@uni.opole.pl], Opole University, Department of Biosystematics, Oleska 22, 45-052 Opole, Poland; Hani F. Kaddumi [blossom_trail@yahoo.com], Eternal River Museum of Natural History, Maroof Al’Rusafi Street, PO Box 11395, Amman 11123, Jordan; Johan Lindgren [johan.lindgren@geol.lu.se], Lund University, Department of Geology, Sölvegatan 12, 223 62 Lund, Sweden.     

Occurrence of the ammonite Goodhallites goodhalli (J. Sowerby) in the Eromanga Basin,Queensland: an index species for the late Albian (Cretaceous)

Mortoniceratid ammonites of the Eromanga Basin of Queensland, although uncommon, are reviewed and reassessed utilising all known collections. Representatives of this group are restricted to the Allaru Formation and almost all specimens are Goodhallites goodhalli, a well-known species from the English Gault. The Allaru Formation overlies the Toolebuc Formation, widely considered to be an essentially isochronous unit because of its unusual sedimentary and geochemical character. Using G. goodhalli, the middle and upper Allaru Formation can be directly correlated with the early late Albian orbignyi and auritus Subzones of the Mortoniceras inflatum Zone as recognized in the reference ammonite zonation embedded in the standard Cretaceous time scale. Overlapping ranges of G. goodhalli and Labeceras and Myloceras allow these common Austral heteromorph genera to be also confidently assigned a late Albian age in Australia, matching their biostratigraphic occurrence in South Africa.     

A new Maastrichtian-Paleocene Azolla species from of Bolivia,with a comparison of the global record of coeval Azolla microfossils

A new heterosporous fern species, Azolla boliviensis sp. nov., is described from latest Maastrichtian (latest Cretaceous) to Paleocene (earliest Palaeogene) terrestrial sediments of the Eslabón and Flora Formations, Subandean belt, Bolivia. The species is represented by dissociated but abundantly co-preserved megasporocarps, megaspores, microsporangia, massulae and microspores. The genus consistently characterizes warm-climate lacustrine settings. Fossil Azolla is first identified around the Early to mid-Cretaceous but the genus apparently underwent dramatic radiation during the Late Cretaceous. Abundant Azolla remains in Bolivia add to this portrait of rapid geographie dispersai and diversification near the close of the Cretaceous. The ranges of many Azolla species span the Cretaceous- Palaeogene boundary and the potential of Azolla to withstand altered environmental conditions, such as periodic frost damage, drought, and salinity change, and its ability to undergo rapid vegetative regeneration in association with nitrogen-fixing cyanobacterial symbionts, suggest that the survival of this group was favoured during the adverse conditions of the end-Cretaceous event.     

Australian Middle Cambrian molluscs and their bearing on early molluscan evolution

Thirty ammonite taxa are recognised in the Wangarlu Mudstone of the Bathurst Island Group from the Cox Peninsula and Shoal Bay, Northern Territory, Australia. Included are a new heteromorph genus Notostreptites, type species N. exilis, and four additional new species and subspecies: Pseudhelicoceras gracilis, Labeceras (L.) tumidum, Labeceras (Appurdiceras) decorum, and Idiohamites dorsetensis laticostatus. The assemblage is best collectively correlated with the Mortoniceras (M.) inflatum Zone of the standard European Albian zonation but some of its members may represent the lower part of the Stoliczkaia dispar Zone. It is broadly correlative with faunas from the Eromanga Basin, which relate to an extensive eastern Australian Late Albian epicontinental sea, but is strikingly different in aspect. The Wangarlu Mudstone assemblage has relatively high diversity and an abundance of cosmopolitan heteromorph taxa well known from Europe and elsewhere, whereas Eromanga Basin assemblages are of relatively low diversity and dominated by Austral heteromorph genera known only from Australasia, southern Africa and Malagasy. The Austral character of Eromanga Basin assemblages is attributed to evolution in a restricted epicontinental sea environment and modest dispersal whereas the continental margin position of the Wangarlu Mudstone ensured an influx of pandemic elements drawn from the mid-Cretaceous world ocean.     

Bryozoans from the late Cretaceous Kahuitara Tuff of the Chatham Islands,New Zealand

Taylor, P.D., & Gordon, D.P., December, 2007. Bryozoans from the Late Cretaceous Kahuitara Tuff of the Chatham Islands, New Zealand. Alcheringa 31, 339-363. ISSN 0311-5518.

Fourteen bryozoan species are described from the Campanian – Maastrichtian Kahuitara Tuff of Pitt Island, substantially increasing the known diversity in this deposit from the two species recorded previously and making it the most diverse bryozoan biota yet described from the Cretaceous of Australasia. Nine of the Kahuitara Tuff bryozoans are cyclostomes, four are cheilostomes, and one is a shell-boring ctenostome. Seven new species are described: Ceriocava hakepaensis sp. nov., Tholopora australis sp. nov., Crisidmonea lanauzeorum sp. nov., Cookobryozoon cretacea sp. nov., Chiplonkarina preeceorum sp. nov. Chiplonkarina bifoliata sp. nov. and Aechmella rangiauriensis sp. nov. The remaining species are left in open nomenclature because of preservational deficiencies or lack of taxon-diagnostic gonozooids. The ctenostome family Cookobryozoidae is subsumed in the Terebriporidae. The new family Chiplonkarinidae is proposed for anascan cheilostomes previously assigned to the paraphyletic Electridae and distinguished by having primarily erect colonies with long, tubular zooids reminiscent of stenolaemates. None of the Kahuitara Tuff bryozoan species is known elsewhere, but all apart from one genus occur in roughly coeval deposits. No families regarded as particularly characteristic of the austral post-Cretaceous are evident. The relatively large number (three) of co-occurring species of Chiplonkarina is notable, as is the dominance of cyclostomes and the first record of Tholopora in the Southern Hemisphere.

Paul D. Taylor [p.taylor@nhm.ac.uk], Department of Palaeontology, Natural History Museum, Cromwell Road, London SW7 5BD, UK; Dennis P. Gordon [d.gordon@niwa.co.nz], National Institute of Water and Atmospheric Research, Private Bag 14-901, Kilbirnie, Wellington, New Zealand; received 7.3.2006, revised 3.9.2006.     

A late Changhsingian (latest Permian) deep-water brachiopod fauna from Guizhou,South China

O’Gorman, J.P. &; Gasparini, Z., 2013. Revision of Sulcusuchus erraini (Sauropterygia, Polycotylidae) from the Upper Cretaceous of Patagonia, Argentina. Alcheringa 37, 161–174. ISSN 0311-5518.

Sulcusuchus erraini, from the upper Campanian–lower Maastrichtian of Patagonia, Argentina, is the only polycotylid from the Southern Hemisphere for which the skull and mandible are known. The diagnosis of the species and genus is emended based on new observations. Sulcusuchus is characterized by the following autapomorphies: (1) deep and broad rostral and mandibular grooves and (2) a wide notch on the posterior margin of the pterygoids that are combined with a part of the body of the basioccipital, forming a wide plate. Several hypotheses about the identity of the structures that could have been housed in the rostral and mandibular grooves are evaluated. Only two of several hypotheses were not discarded. The first is that the grooves may have accommodated oral glands (supralabial and sublabial), but the biological role of such glands could not be inferred. The second hypothesis is the presence of special structures of an electrosensitive and/or mechanosensitive nature, which might allow the detection of infaunal or semi-infaunal food in soft substrates, as is represented in modern analogues, such as dolphins.

José P. O’Gorman [joseogorman@fcnym.unlp.edu.ar] and Zulma Gasparini [zgaspari@fcnym.unlp.edu.ar], División Paleontología Vertebrados, Museo de La Plata, Universidad Nacional de La Plata, Paseo del Bosque s/n., B1900FWA La Plata, Argentina. Also affiliated with Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Rivadavia 1917 (C1033AAJ), Ciudad Autónoma de Buenos Aires, Argentina and CONICET: Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina Received 5.6.2012; revised 31.7.2012; accepted 4.9.2012.     

Elasmosaurs (Sauropterygia,Plesiosauria) from the La Colonia Formation (Campanian–Maastrichtian), Argentina

O’Gorman, J.P., Salgado, L., Varela, J., & Parras, A., 2013. Elasmosaurs (Sauropterygia, Plesiosauria) from the La Colonia Formation (Campanian–Maastrichtian), Argentina. Alcheringa 37, 257–265. ISSN 0311-5518.

Elasmosaur postcranial remains from the La Colonia Formation (Campanian–Maastrichtian), Chubut Province, Patagonia, Argentina, are described. The new material has small dimensions and caudal vertebrae with parapophyses strongly projected laterally—characters shared with some Elasmosauridae indet. from the coeval Allen Formation, Río Negro Province, Argentina. These features reinforce the similarities between the plesiosaur faunas to the north and south of the Somún Curá Plateau. The small size of these elasmosaurs may be palaeoecologically related to the marginal marine depositional environment of the sedimentary host rocks.

José P. O’Gorman [joseogorman@fcnym.unlp.edu.ar], División Paleontología Vertebrados, Museo de La Plata, Universidad Nacional de La Plata, Paseo del Bosque s/n., B1900FWA, La Plata, Argentina and [CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas)]; Leonardo Salgado [salgadoleito@yahoo.com.ar], Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro, Isidro Lobo y Belgrano, 8332 General Roca, Argentina and [CONICET]; Julio Varela [julioadrianvarela@hotmail.com], and Ana Parras [aparras@exactas.unlpam.edu.ar], INCITAP (CONICET-UNLPam), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de La Pampa, Uruguay 151, 6300 Santa Rosa, La Pampa, Argentina. Received 27.7.2012; revised 19.10.2012; accepted 27.10.2012.     

Upper Cretaceous volcanoclastic deposits from the Haţeg basin,south Carpathians (Romania): K-Ar ages and intrabasinal correlation

In order to constrain the age of the Upper Cretaceous continental Densuş-Ciula Formation from the Haţeg basin, South Carpathians, and correlate it with the other continental unit that occurs in the region, the Sanpetru Formation, we separated and dated by the K-Ar method biotites and amphiboles from volcanoclastic deposits. The mineral phases analysed are from two tuff layers and volcanic bombs cropping out near Rachitova village. Two tuff layers from the Densuş-Ciula Formation give early Maastrichtian ages of 69.8±1.3 and 71.3±1.6 Ma, respectively. The ages determined for the tuff layers constrain the age of deposition for the Densuş-Ciula Formation and enable further correlations with the available palaeomagnetic data from the deposits occurring along the Sibişel Valley that belong to the Sanpetru Formation. The volcanic bombs collected near to Răchitova village are andesites and dacites. The age determined by K-Ar method on hornblende separated from a volcanic bomb is 82.7±1.5 Ma, which is older than the underlying Campanian marine deposits in turbidite facies. This suggests that the volcanic bombs were re-deposited during the early Maastrichtian. Thus, the volcanics found at Răchitova have at least two origins: one type is related to an explosive synsedimentary volcanic activity, and the other type is represented by older andesitic/dacitic bombs, which most probably originate from a volcanic centre situated in the Haţeg region.     

First record of the ichthyodectiform fish Xiphactinus (Teleostei) from Patagonia,Argentina

Abstract

We report the first record of the genus Xiphactinus from southern South America. The recovered fossil material consists of an associated maxilla and abdominal vertebra, probably derived from latest Maastrichtian marine deposits of the Salamanca Formation in Chubut Province, Argentina. Xiphactinus has been widely reported from Late Cretaceous strata throughout the Northern Hemisphere, although to date, equivalent Southern Hemisphere occurrences include only a single specimen from Venezuela. Our new discovery thus indicates that Xiphactinus had a much more cosmopolitan distribution, encompassing the southern paleolatitudinal extremities of South America during the terminal Cretaceous.

Julieta J. De Pasqua [julietadepasqua@gmail.com], Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’, Av. Ángel Gallardo, 470, C1405DJR, Buenos Aires, Argentina;

Federico L. Agnolin [fedeagnolin@yahoo.com.ar], Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’, Av. Ángel Gallardo, 470, C1405DJR, Buenos Aires, Argentina. CONICET; Fundación de Historia Natural ‘Félix de Azara’, Departamento de Ciencias Naturales y Antropología, Universidad Maimónides; Hidalgo 775 piso 7, C1405BDB, Buenos Aires, Argentina;

Sergio Bogan [sergiobogan@yahoo.com.ar], Fundación de Historia Natural ‘Félix de Azara’, Departamento de Ciencias Naturales y Antropología, Universidad Maimónides; Hidalgo 775 piso 7, C1405BDB, Buenos Aires, Argentina.     

First evidence of a Late Cretaceous sea turtle from Australia

The isolated scapula of a chelonioid sea turtle is described from the Upper Cretaceous (upper Maastrichtian) Miria Formation of the Giralia Ranges in Western Australia. Character states including the wide angle of divergence between the scapular processes (possibly reaching 140°), projection of the glenoid on a constricted scapular neck, and highly vascular glenoid articular surfaces suggest affinity with dermochelyoids—the most diverse and geographically widespread clade of Mesozoic chelonioids. The Miria Formation chelonioid scapula constitutes the first definitive record of a Late Cretaceous sea turtle from Australia and is one of the few occurrences thus far documented from Upper Cretaceous–Paleogene deposits in the Southern Hemisphere.     

Organic–inorganic rock–fluid interactions in stylolitic micro‐environments of carbonate rocks: a FIB‐TEM study combined with a hydrogeochemical modelling approach

Stylolites and the interfaces to the host limestone have been investigated by means of a multidisciplinary analytical approach (thin section microscopy, FIB‐TEM, organic geochemistry and petrography). Carbonate dissolution assuming different boundary conditions was simulated by applying a generic hydrogeochemical modelling approach. It is the conceptual approach to characterize and quantify traceable organic–inorganic interactions in stylolites dependent on organic matter type and its thermal maturity, and to follow stylolite formation in carbonates as result of organic matter reactivity rather than pressure solution as a main control. The investigated stylolite samples are of Upper Permian (Lopingian, Zechstein), Middle Triassic (Muschelkalk) and Late Cretaceous (Maastrichtian) age and always contain marine organic matter. The thermal maturity of the organic matter ranges from the pre‐oil generation zone (0.4–0.5% R_r) to the stage of dry gas generation (>1.3% R_r). The results of the generic hydrogeochemical modelling indicate a sharp increase of calcite dissolution and the beginning of stylolite formation at approximately 40°C, which is equivalent to a depth of less than 800 m under hydrostatic conditions considering a geothermal gradient of 30°C and a surface mean temperature of 20°C. This temperature corresponds to the pre‐oil window when kerogens release an aqueous fluid enriched in carbon dioxide and organic acids. This aqueous fluid may change the existing pore water pH or alkalinity and causes dissolution of carbonate, feldspar and quartz, and clay mineral precipitation along the stylolite. Dissolution of limestone and dolostone leads to reprecipitation of calcite or dolomite opposite of the dissolution side, which indicates only localized mass redistribution. All these integrated hydrogeochemical processes are coupled to the generation of water during organic matter maturation. In all of the calculated hydrogeochemical scenarios, H₂O is a reaction product and its formation supports the suggested hypothesis.     

A new record of an aristonectine elasmosaurid (Sauropterygia,Plesiosauria) from the Upper Cretaceous of New Zealand: implications for the Mauisaurus haasti Hector, 1874 hypodigm

O’Gorman, J.P., Otero, R.A. & Hiller, N., 2014. A new record of an aristonectine elasmosaurid (Sauropterygia, Plesiosauria) from the Upper Cretaceous of New Zealand: implications for the Mauisaurus haasti Hector, 1874 Hector, J., 1874. On the fossil Reptilia of New Zealand. Transactions and Proceedings of the New Zealand Institute 6, 333–358. [Google Scholar] hypodigm. Alcheringa 38, 504–512. ISSN 0311-5518

An indeterminate aristonectine elasmosaurid is recorded from a lower Maastrichtian bed of the Conway Formation, Waipara River, South Island, New Zealand. The described specimen (CM Zfr 104), previously considered part of the hypodigm of Mauisaurus haasti, came from the upper part of the Alterbidinium acutulum biozone, the same zone from which the only well-known aristonectine from New Zealand, Kaiwhekea katiki, is recorded. The cervical vertebrae of CM Zfr 104 have the same distinctive features (i.e., with extremely broad rather than long centra) as those from previously recorded juvenile aristonectines from Argentina, Chile and Antarctica. This new record is congruent with the biogeographic relationships of Cretaceous marine amniotes from the Weddellian Palaeobiogeographic Province (i.e., Patagonia, western Antarctica, New Zealand and southeastern Australia). Therefore, this type of vertebra is regarded as a distinctive feature of the Weddellian aristonectine elasmosaurids.

José P. O’Gorman [joseogorman@fcnym.unlp.edu.ar], División Paleontología Vertebrados, Museo de La Plata, Universidad Nacional de La Plata, Paseo del Bosque s/n., B1900FWA, La Plata, Argentina; [CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas)]; Rodrigo A. Otero [paracrioceras@gmail.com], Red Paleontológica U-Chile. Laboratorio de Ontogenia y Filogenia, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Av. Las Palmeras 3425, Santiago, Chile; Norton Hiller, [norton.hiller@canterbury.ac.nz], Department of Geological Sciences, University of Canterbury, PB 4800, Christchurch, 8001, New Zealand and Canterbury Museum, Rolleston Avenue, Christchurch, New Zealand, 8013.     

Metaceratodus kaopen comb. nov. and M. wichmanni comb. nov., two Late Cretaceous South American species of an austral lungfish genus (Dipnoi)

Cione, A.L. & Gouiric-Cavalli, S., June 2012. Metaceratodus kaopen comb. nov. and M. wichmanni comb. nov., two Late Cretaceous South American species of an austral lungfish genus (Dipnoi). Alcheringa 36, 203–216. ISSN 0311-5518.

Metaceratodus wollastoni, an Australian species, was reported from Upper Cretaceous beds of Patagonia in 1997. Later, three new species (Ceratodus wichmanni, Ptychoceratodus kaopen and Ptychoceratodus cionei), based on scarce material, were described from the same region. Two of these species were later referred to Ferganoceratodus. After examining much more abundant and better-preserved material, we conclude that neither the occurrence of Metaceratodus wollastoni nor those of Ptychoceratodus and Ferganoceratodus in the Cretaceous of South America are supported. We consider that C. wichmanni and P. cionei are synonyms and we reassign the three putative species to Metaceratodus under two new combinations: M. kaopen comb. nov. and M. wichmanni comb. nov. Both differ from the other species of the genus in having pits over most of the occlusal surface and a different occlusal profile of the tooth plate, and most have four ridges in the lower and upper tooth plates. Metaceratodus wichmanni differs from M. kaopen in oclussal profile, inner angle, and symphysis development among other features. Metaceratodus kaopen is known from the upper Santonian–lower Campanian Anacleto Formation of Río Negro province and M. wichmanni from upper Campanian–lower Maastrichtian units of Chubut, Río Negro, Neuquén and Mendoza provinces, Argentina. The occurrence of Metaceratodus in southern South America corroborates a close biogeographical relationship with Australia in the latest Cretaceous.

Alberto Luis Cione [acione@museo.fcnym.unlp.edu.ar] and Soledad Gouiric-Cavalli [sgouiric@museo.fcnym.unlp.edu.ar], División Paleontología Vertebrados, Museo de La Plata, Paseo del Bosque s/n, W1900FWA La Plata, Argentina. Received 23.11.2010, revised 11.7.2011, accepted 7.8.2011.

     

A palaeobiogeographical synthesis of Australasian Mesozoic marine tetrapods

Kear, B.P., Fordyce, R.E., Hiller, N. & Siversson, M., December 2017. A palaeobiogeographical synthesis of Australasian Mesozoic marine tetrapods. Alcheringa 42, 461-486. ISSN 0311-5518.

THE LAST 15 years has witnessed a blossoming of research on Australasian Mesozoic marine tetrapod fossils. Much of this work has focused on amniotes, particularly those from the prolific Lower Cretaceous (Aptian–Albian) Lagerstätten of the Eromanga Basin in central and eastern Australia, and Upper Cretaceous (Campanian–Maastrichtian) sequences of the North and South islands of New Zealand. However, rare and less popularized remains have also been found in Lower Triassic–mid-Cretaceous rocks from Australia, New Zealand and the Chatham Islands, and on the tectonically proximal landmasses of New Caledonia and Timor. Currently identified taxa include estuarine–paralic rhytidostean, brachyopid, capitosaurian and trematosaurian temnospondyls from the earliest Triassic (Induan–Olenekian), Middle–Late Triassic (Anisian–Norian) eosauropterygians, and mixosaurian, shastasaurian and euichthyosaurian ichthyosaurians, Early–Middle Jurassic (Sinemurian–Bajocian) ichthyosaurians, together with plesiosauroid and rhomaleosaurid-like plesiosaurians, and diverse Early (Aptian–Albian) through to Late Cretaceous (Campanian–Maastrichtian) elasmosaurid, leptocleidid, polycotylid, probable cryptoclidid and pliosaurid plesiosaurians, as well as ophthalmosaurid ichthyosaurians, sea turtles incorporating protostegids, and mosasaurid squamates. This faunal succession evidences almost continuous occupation of southern high-palaeolatitude seas, and repeated endemic diversifications (including nascent members of some key lineages) amongst emigrant cosmopolitan clades. The primary dispersal routes are likely to have been peri-Gondwanan, with coastal migrations along the western Tethys and polar margins of the Panthalassan Ocean. However, augmentation by increasing continental fragmentation and seaway corridor connectivity probably occurred from the Middle Jurassic to Late Cretaceous. Latest Cretaceous mosasaurid and elasmosaurid taxa also reveal regional affinities with the emergent western Pacific and Weddellian austral bioprovinces. The extreme rarity, or complete absence, of many major groups prevalent elsewhere in Gondwana (e.g., tanystropheids, Triassic sauropterygians, bothremydid marine turtles, thalattosuchians and dyrosaurid crocodylomorphs) is conspicuous, and might be related to stratigraphical/collecting biases, or the predominantly higher-palaeolatitude, cooler-water Mesozoic palaeogeography of the Australasian region. Although the burgeoning record is substantial, much still awaits discovery and adequate documentation; thus Australasia is still one of the most exciting prospects for future insights into the global history of Mesozoic marine tetrapods.

Benjamin P. Kear* [benjamin.kear@em.uu.se] Museum of Evolution, Uppsala University, Norbyvägen 16, SE-752 36 Uppsala, Sweden; R. Ewan Fordyce [ewan.fordyce@otago.ac.nz] Department of Geology, University of Otago, Post Box 56, Dunedin 9054, New Zealand; Norton Hiller [norton.hiller@gmail.com] Canterbury Museum, Rolleston Avenue, Christchurch 8013, New Zealand; Mikael Siversson [mikael.siversson@museum.wa.gov.au] Western Australian Museum, 49 Kew Street, Welshpool, Western Australia 6106.     

Utilizing U–Pb CA-TIMS dating to calibrate the Middle to Late Jurassic spore-pollen zonation of the Surat Basin,Australia to the geological time-scale

Wainman, C.C., Hannaford, C., Mantle, D. & McCabe, P.J., April.2018. Utilizing U–Pb CA-TIMS dating to calibrate the Middle to Late Jurassic spore-pollen zonation of the Surat Basin, Australia to the geological time-scale. Alcheringa XX, xx-xx.

Spore-pollen palynostratigraphy is commonly used to subdivide and correlate Jurassic continental successions in eastern Australia and thus aid the construction of geological models for the petroleum and coal industries. However, the current spore-pollen framework has only been tenuously calibrated to the geological time-scale. Age determinations are reliant on indirect correlations of ammonite and dinoflagellate assemblages from New Zealand, the North West Shelf of Australia and Southeast Asia to the standard European stages. New uranium-lead chemical abrasion thermal ionization mass spectrometry (U–Pb CA-TIMS) dates from 19 tuff beds in the Middle–Upper Jurassic Injune Creek Group of the Surat Basin enables regional spore-pollen palynostratigraphic zones to be precisely dated for the first time. These results show the base of the APJ4.2 and APJ4.3 subzones are similar in age to previous estimates (Middle Jurassic, Bathonian) from indirect palynostratigraphic correlation. However, the base of the APJ5 Zone and the APJ6.1 Subzone may be somewhat younger than previously estimated, possibly by as much as 2.5 and 4.2 Myrs, respectively. The continued utilization of U–Pb CA-TIMS dates will further refine the absolute ages of these zones, improve the inter- and intra-basinal correlation of Middle–Upper Jurassic strata in eastern Australian basins and greatly enhance intercontinental correlations.

Carmine Christopher Wainman [carmine.wainman@adelaide.edu.au] and Peter James McCabe [peter.mccabe@adelaide,edu.au] Australian School of Petroleum, University of Adelaide, SA, 5005, Australia; Carey Hannaford [carey.hannaford@mgpalaeo.com.au] and Daniel Mantle [dan.mantle@mgpalaeo.com.au] MGPalaeo Pty Ltd, 5 Arvida Street, Malaga, WA, 6090, WA, Australia.