Evidence of a Supervolcano Eruption From Albian Cretaceous Australia

The answers are blowin' in the wind: Ultra-distal ashfall zircons, indicators of Cretaceous super-eruptions in eastern Gondwana

Authors:

Barham et al

Abstract:

An Early Cretaceous siliceous large igneous province (SLIP) that developed on the eastern margin of Gondwana produced some of the most voluminous siliceous volcaniclastic deposits known globally. We report U-Pb ages and trace-element and Hf-isotopic signatures of detrital zircons from the Madura Shelf (onshore Bight Basin), Western Australia. These zircons include a geochemically distinct 106 Ma component with age and Hf characteristics that match SLIP volcanics some 2300 km distant in eastern Australia. This young subpopulation shows limited grain abrasion, which contrasts with older detrital components that are stratigraphically persistent. Regional detrital zircon provenance demonstrates that sediment routing systems were disconnected in the eastern and western Bight Basin, negating terrestrial transport mechanisms as a possible vector of the zircons from the SLIP to their recovered position. Palynology indicates that the 106 Ma zircons are syn-depositional, and we interpret them as being significantly transported in an eruption plume. Given the grain size and distance from source, such distal zircon emplacement suggests previously undocumented 106 Ma super-eruptions. The 106 Ma zircons likely reflect Southern Hemisphere winter eruptions when tropospheric polar easterly winds would have been favored across southeastern Australia.

Camouflage Evolution in Albian/Cenomanian Cretacous Insect Preserved in Amber

Those who go to a masked ball consciously slip into a different role, in order to avoid being recognized so quickly. Insects were already doing something very similar in the Cretaceous: They cloaked themselves in pieces of plants, grains of sand, or the remains of their prey, in order, for example, to be invisible to predators. An international research team, with participation from the University of Bonn, has now investigated such "invisibility cloaks" encased in amber. The custom-tailored "costumes" also permit conclusions about the habitat at the time. The results have now been published in the journal "Science Advances".

The larva of the lacewing attacks a pseudoscorpion and uses its powerful mouthparts to suck it dry. The larva then puts the remains of the dead prey on its back. The outlines of the lacewing are now unrecognizable. It looks more like a dead pseudoscorpion. This camouflage protects the lacewing against being recognized by predators and at the same makes it easier to hunt its own prey. "With this 'disguise', the lacewing larva pretends to be someone completely different", says Prof. Dr. Jes Rust of the Steinmann-Institute of the University of Bonn. "Using the pieces of its prey, it even takes on the smell of the pseudoscorpion".

The scene plays out in the Cretaceous and is recorded as a "snapshot" in amber. A research team under Dr. Bo Wang of the State Key Laboratory of Paleobiology and Stratigraphy in Nanjing (China) worked together with paleontologists from the University of Bonn and other scientists from China, USA, France, and England to examine a total of 35 insects preserved in amber. With the aid of grains of sand, plant residue, wood fibers, dust, or even the lifeless shells of their victims, the larvae achieved camouflage to perfection. The amber samples come from Myanmar, France, and Lebanon.

link.

Turns out Sauropods Liked Pasta

First sauropod bones from Italy offer new insights on the radiation of Titanosauria between Africa and Europe

Authors:

Dal Sasso et al

Abstract:

Here we describe the first sauropod skeletal remains from the Italian peninsula that also represent the earliest record of titanosaurs in Southern Europe. Scattered bones, including an almost complete anterior caudal vertebra, were found in Cretaceous (Aptian–Albian) marine deposits, some 50 km East of Rome. The vertebra shows a bizarre and perhaps unique orientation of the zygapophyseal articular facets that renders their interpretation problematic. Phylogenetic retrofitting tests support the placement of the Italian titanosaur among basal lithostrotians. Palaeobiogeographic analysis based on the resulting phyletic relationships suggests an Afro-Eurasian route for the ancestors of the Italian titanosaur, a scenario compatible with the palaeogeographic evolution of the Italian microplates during the Cretaceous. Together with previously recorded titanosaurian-like ichnites from a Cenomanian locality in Latium, this new find suggests a quite long emersion for the Apenninic carbonate platform. We suggest that the Italian titanosaur was member of a population that crossed the western Tethys Sea through a “filtering bridge” composed of a chain of ephemeral islands and peninsulae, known as Periadriatic (Adria) carbonate platforms, that connected sporadically Africa and Europe since the Early Cretaceous.

Glacial dropstones in the western Tethys during the late Aptian–early Albian cold snap

Glacial dropstones in the western Tethys during the late Aptian–early Albian cold snap: Palaeoclimate and palaeogeographic implications for the mid-Cretaceous

Authors:

Rodríguez-López et al

Abstract:

The late Jurassic–early Cretaceous is commonly considered the only cold climatic interval in Earth history without any direct evidence of polar ice. A newly discovered dropstone-bearing interval from the subtropical Iberian Basin (western Tethys) is described and provides evidence of contemporaneous polar glaciation. This interval is correlated laterally for 4.8 km and contains a boulder and two cobble-sized quartzite dropstones that are encased in mid-Cretaceous fissile black shales and fine-grained sandstones. Based on previously published dimensions of similar large clasts, only glacial dropstones and impact ejecta blocks reach the dimensions of the boulder-sized dropstone reported from Iberia. The dropstones show morphological features compatible with glacial transport and abrasion in a subglacial setting which closely resembles the features observed in recent glacial boulders exposed near the snouts of glaciers in Iceland. These Late Aptian dropstones from Spain correlate with many other similar erratics in the northern and southern palaeohemispheres, and suggest that ice sheets formed around the palaeo-North Pole during certain periods of the early Cretaceous. Our results and associated evidence such as the occurrence of glendonites, tillites, moderate- to high-amplitude sea-level oscillations worldwide, minimum pCO2 concentrations, variation in calcareous nannofossil assemblages from low and high latitudes and isotopic excursions suggest that during the mid-Cretaceous there were periods of ice growth and decay that influenced the palaeotemperature, palaeoecology and sedimentology of the marine realm. The new data from Iberia are supported by recent results from Arctic Canada that indicate cool shelves and a mid-Cretaceous cold snap that developed for ~ 6 Myr between 118 and 112 Ma. The late Aptian dropstones reported in eastern Iberia were likely transported from high northern latitudes towards subtropical ones in the western Tethys by an extreme iceberg drift similar to those occurring at the present day in the Atlantic Ocean. Icebergs released from a northern fringing ice sheet may have travelled southwards through the Greenland–Norwegian Seaway.

Potentially NO Aptian and Albian Cretaceous Atmospheric CO2 changes during oceanic anoxic events

Aptian and Albian atmospheric CO2 changes during oceanic anoxic events: Evidence from fossil Ginkgo cuticles in Jilin Province, Northeast China

Authors:

Sun et al

Abstract:

The Early Cretaceous was a time with super-greenhouse conditions and episodic global oceanic anoxic events. However, relative timing of atmospheric CO2 emissions and oceanic anoxic events, and their causal relationships remain matters of debate. Using the stomatal index approach, well-preserved fossil cuticles of Ginkgo from the Lower Cretaceous Changcai Formation, eastern Jilin, and from the Lower Cretaceous Yingcheng Formation, central Jilin, Northeast China, were investigated to reconstruct atmospheric CO2 concentrations during the Aptian and earliest Albian (Early Cretaceous). The results indicate that the CO2 concentrations reached 1098–1142 ppmv (Carboniferous standardization) or 970–1305 ppmv (regression function) during the Aptian and earliest Albian. Our estimates of palaeoatmospheric CO2 concentrations during the earliest Albian (OAE 1b) are slightly higher than the data between the early Aptian Selli (OAE 1a) and the middle Aptian Fallot OAEs; this may indicate the absence of any great emissions of CO2 during the latest Aptian and earliest Albian.

Why did the Stegosaurs go Extinct in the Cretaceous?

Without doubt, stegosaurs were adversely affected by new conditions in the Cretaceous. Available data suggests that, right after their Jurassic heyday, stegosaurs suffered a loss of diversity similar to what sauropods endured - 57-89%. After this first setback, they were further battered, by Barremian time c. 127 Ma. Plated dinosaurs apparently vanished everywhere, except in Asia, where their last occurrences are dated Aptian-Albian. By mid K at the latest, Stegosauria was entirely gone. What caused plated beasts to wane and die out?

In their 2009 paper, Diversity patterns amongst herbivorous dinosaurs and plants during the Cretaceous, Butler et al. note an apparent correlation between the waning of certain plants (cycads, cycadophytes and bennattitalles) and the demise of stegosaurs. Citing earlier works suggesting an ecological association of plated dinosaurs and cycads (and close relatives) they suggest the disappearance of stegosaurs, from the start of the early Cretaceous to its end, mirrored the decline of such vegetation.

With their narrow snouts, stegosaurs do appear to have been specialized feeders, essentially limited to a specific type of plant. Ergo, they may have been vulnerable to loss of such flora. The available evidence however, suggests other factors may have been equally important, if not more so.

link.

Lizards Preserved in Albian/Cenomanian Cretaceous Amber From Myanmar

Mid-Cretaceous amber fossils illuminate the past diversity of tropical lizards

Authors:

Daza et al

Abstract:

Modern tropical forests harbor an enormous diversity of squamates, but fossilization in such environments is uncommon and little is known about tropical lizard assemblages of the Mesozoic. We report the oldest lizard assemblage preserved in amber, providing insight into the poorly preserved but potentially diverse mid-Cretaceous paleotropics. Twelve specimens from the Albian-Cenomanian boundary of Myanmar (99 Ma) preserve fine details of soft tissue and osteology, and high-resolution x-ray computed tomography permits detailed comparisons to extant and extinct lizards. The extraordinary preservation allows several specimens to be confidently assigned to groups including stem Gekkota and stem Chamaleonidae. Other taxa are assignable to crown clades on the basis of similar traits. The detailed preservation of osteological and soft tissue characters in these specimens may facilitate their precise phylogenetic placement, making them useful calibration points for molecular divergence time estimates and potential keys for resolving conflicts in higher-order squamate relationships.

A Lamniform Shark From Albian Cretaceous Texas Grew 6.3m (20+ ft) in 18 Years

Ontogeny and life history of a large lamniform shark from the Early Cretaceous of North America

Authors:

Frederickson et al

Abstract:

Due to an incomplete fossil record, little is known about lamniform shark life history from the Early Cretaceous of North America. Recent discoveries have shown that during this time, some lamniformes reached gigantic sizes (greater than 6–8 m in total length) not seen in earlier species. Given the importance of life history to understand how organisms reach such sizes, we conducted an ontogenetic analysis on three very large shark vertebrae, representing a single individual from the Lower Cretaceous (Albian) Duck Creek Formation of Texas. Using three different techniques (computed tomography, histological sectioning, and surface texture analysis), we were able to show that this individual was born at a relatively small size and subsequently grew at rapid rate, achieving a total length of over 6.3 m in approximately 18 years; a rate not observed in any other Cretaceous species. Comparison of the different aging techniques yielded complementary results; however, surface texture analysis produced the most complete ontogenetic record for this specimen. More work is needed to determine broad patterns in the life history evolution of giant Early Cretaceous lamniform sharks.

Palm Pollen (!) From Barremian/Albian Cretaceous Patagonia

Early Cretaceous palm pollen tetrads from Patagonia, Argentina

Authors:

Martinez et al

Abstract:

Pollen tetrads and monads of spiny pollen grains with close affinities to palms have been found in several localities from the Lower Cretaceous (Barremian-Albian) of the Austral Basin (Magallanes), Patagonia (Argentina). When found dispersed, spiny and zonasulcate pollen grains, are commonly referred to the fossil genus Spinizonocolpites Muller, with close affinities to the extant palm Nypa. The Patagonian specimens were compared with fossil and extant members of the Arecaceae, showing close similarities in shape and sculpture with the primitive members of the subfamily Calamoideae. Nypa produces tetragonal tetrads different from the tetrahedral tetrads of the Spinizonocolpites-type recovered from Patagonia. The specimens were studied with LM and SEM. The polarity, aperture orientation and tetrad type allow segregating the Patagonian grains from the Nypoideae and relating it to the Calamoideae subfamily. These records suggest an antique origin of monocots and a probably initial diversification of calamoid palms during the Early Cretaceous in high latitudes of Gondwana. The presence of palmae during the Early Cretaceous in southern South America suggests a warm and humid climate, similar to that found in present days at tropics.

Spinolestes xenarthrosus: a Spiny, Furry Triconodont Mammal From Barremanian/Aptian Cretaceous Spain

A Cretaceous eutriconodont and integument evolution in early mammals

Authors:

Martin et al

Abstract:

The Mesozoic era (252–66 million years ago), known as the domain of dinosaurs, witnessed a remarkable ecomorphological diversity of early mammals. The key mammalian characteristics originated during this period and were prerequisite for their evolutionary success after extinction of the non-avian dinosaurs 66 million years ago. Many ecomorphotypes familiar to modern mammal fauna evolved independently early in mammalian evolutionary history. Here we report a 125-million-year-old eutriconodontan mammal from Spain with extraordinary preservation of skin and pelage that extends the record of key mammalian integumentary features into the Mesozoic era. The new mammalian specimen exhibits such typical mammalian features as pelage, mane, pinna, and a variety of skin structures: keratinous dermal scutes, protospines composed of hair-like tubules, and compound follicles with primary and secondary hairs. The skin structures of this new Mesozoic mammal encompass the same combination of integumentary features as those evolved independently in other crown Mammalia, with similarly broad structural variations as in extant mammals. Soft tissues in the thorax and abdomen (alveolar lungs and liver) suggest the presence of a muscular diaphragm. The eutriconodont has molariform tooth replacement, ossified Meckel’s cartilage of the middle ear, and specialized xenarthrous articulations of posterior dorsal vertebrae, convergent with extant xenarthran mammals, which strengthened the vertebral column for locomotion.

pop sci write up #1,  #2 and #3.

A Conifer Woodland From Aptian/Albanian Cretaceous Patagonia

Aptian–Albian Cupressaceae (sensu stricto) woods from Cañadón Asfalto Basin, Patagonia Argentina

Authors:

Brea et al

Abstract:

This paper describes the first macrofloristic record from Los Adobes Formation (Chubut Group) in Cañadón Asfalto Basin (Patagonia, Chubut Province, Argentina). The studied fossils were recovered from the Aptian–Albian Bardas Coloradas Member, and consist of silicified woods preserved in fluvial channel deposits. One wood shows homocellular rays with smooth radial and tangential walls, diffuse axial parenchyma, tracheid pitting of the abietinoid type and cross-field pitting cupressoid usually ordered in rows and columns indicating placement within Cupressinoxylon hallei Kräusel. This fossil tree resembles some members of the extant Cupressaceae s.s., as Austrocedrus chilensis (D. Don) Pic. Serm. & Bizzarri, Pilgerodendron uviferum (D. Don) Florin, Fitzroya cupressoide (Molina) I. M. Johnst. and Libocedrus plumosa (D. Don) Druce. Due to poor preservation the other fossil wood specimen was assigned to cf. Cupressinoxylon Göppert 1850 nom. cons. prop. This is the first unequivocal record of C. hallei from the Cretaceous of South America and the oldest reliable record of the Callitroideae, indicating that this subfamily was well established since the mid-Cretaceous in the Southern Hemisphere.

Two new Species of Gobiconodon Mammals From Aptian/Albian Cretaceous China

Two new species of Gobiconodon (Mammalia, Eutriconodonta, Gobiconodontidae) from the Lower Cretaceous Shahai and Fuxin formations, northeastern China

Authors:

Kusuhashi et al

Abstract:

Two new gobiconodontid mammals, Gobiconodon tomidaisp. nov. and Gobiconodon haizhouensissp. nov., from the Lower Cretaceous (Aptian to Albian) Shahai and Fuxin Formations, respectively, in Liaoning Province, northeastern China, are described. Gobiconodon tomidaisp. nov. is a small-sized species of the genus characterised by the lower dental formula 2.1.2.5, a double-rooted p2, the molariform crown being mesiodistally longer than tall, and a distinct and almost continuous lingual cingulid on m2–m4. Gobiconodon haizhouensissp. nov. is of similar size to Gobiconodon tomidaisp. nov. and is characterised by the lower dental formula 2.1.3.5, the molariform crown being slightly taller than the mesiodistal length, and a well-developed and almost continuous lingual cingulid on m1–m3. The new materials indicate that the upper molariform count of most species of Gobiconodon is likely to be four, one less than the lower molariform count. Gobiconodon is the second mammalian genus common to the Jehol and Fuxin mammalian faunas.

Diverse Flowering Plant Pollen Found in Albian Cretaceous China

Palynology of the Early Cretaceous Hanxia Section in the Jiuquan Basin, Northwest China: The discovery of diverse early angiosperm pollen and paleoclimatic significance

Authors:

Zhang et al

Abstract:

The Lower Cretaceous deposits of the Jiuquan Basin (Northwestern China) located in central Asia are famous for the abundant and diverse fossil products with distinct characteristics of Jehol Biota. However, few early angiosperm remains have been published in their entirety. This study presents a palynomorph record from the recently reported fossil-bearing Zhonggou Formation of the Hanxia Section in the Jiuquan Basin. Here, we first discovered abundant and diverse angiosperm pollen with 16 taxa, which can be classified into four morphological types: tricolpate, polyaperturate, monosulcate and etrachotomocolpate apertures. The palynomorph assemblages contain a large number of biostratigraphically significant palynomorphs, such as numerically abundant tricolpate and rare polyaperturate angiosperm pollen grains, which indicate an Early Albian age for the Zhonggou Formation of the Hanxia Section. The overall palynomorph assemblage is dominated by the Perinopollenites, followed by the Classopollis; bisaccate pollen indicate Taxodiaceae-dominant vegetation types. As such, a relatively temperate and humid climatic condition is suggested for this area. Furthermore, two palynomorph assemblages can be distinguished in a stratigraphically upward order with an obviously increasing Classopollis content, indicating a gradual aridification trend during the Early Albian. This climatic change may affect the diversification of early angiosperms based on the correlation with the stratigraphic distribution of discovered angiosperm pollen.

The Phylogenetics of 5 Mammals From Aptian/Albian Cretaceous Texas and Oklahoma

Taxonomic revision of tribosphenic mammals from the Lower Cretaceous Antlers Formation of Texas and Oklahoma, USA.

Author:

Averianov

Abstract:

There are five taxa of tribosphenic mammals in the Early Cretaceous Antlers Formation of Texas and Oklahoma, USA: a basal stem therian (Kermackia texana), stem therians near the eutherian-metatherian dichotomy (Holoclemensia texana and Pappotherium pattersoni), and stem marsupials (Atokatheridium boreni and Oklatheridium szalayi). K. texana has a primitive therian postcanine formula with three molars, replacement of p5, M3 with low protocone and no conules, lower molars with a large trigonid angle, oblique protocristid, paraconid smaller than metaconid (except m3), strong distal metacristid, narrow talonid, small talonid basin, and small entoconid (absent on m3). H. texana also has replacement in the fifth premolar locus and three molars. It is more derived in having a larger protoconal region with higher protocone and conules present, lack of distal metacristid, smaller trigonid angle, transverse protocristid, and wide talonid with larger talonid basin. It is similar to Eutheria by having M1 with reduced ectoflexus, semimolariform p5, and low trigonid angle with transverse protocristid. Holoclemensia cannot be referred to Eutheria because of the lack of the second rank postvallum/prevallid shear and unwinged conules. P. pattersoni (=Slaughteria eruptens) has replacement in the fifth premolar position, premolariform p5, and three molars (symplesiomorphies for Theria). It is more derived than Holoclemensia in having a wider and shorter talonid. Pappotherium is similar to Eutheria in having a low trigonid angle, transverse protocristid, and the cristid obliqua labial to the protocristid notch. It cannot be attributed to the Eutheria because of the narrow protoconal region, low protocone, small conules lacking internal cristae, postprotocrista not extending labially past the metacone base, and a small talonid basin. Atokatheridium boreni and Oklatheridium szalayi (=O. minax, syn. nov.) have four molars and emphasis on the postvallum/prevallid shear (large metacone on M2, strong postmetacrista, paraconid higher than metaconid). These taxa cannot be attributed to the Deltatheroida because of large protoconal region with winged conules. Oklatheridium is further different from the Deltatheroida in having a wider talonid and better developed entoconid.

A New "Megaraptorid" Theropod Found in Albian Cretaceous Australia

A large-clawed theropod (Dinosauria: Tetanurae) from the Lower Cretaceous of Australia and the Gondwanan origin of megaraptorid theropods

Authors:

Bell et al

Abstract:

Megaraptoridae comprises a clade of enigmatic Gondwanan theropods with characteristic hypertrophied claws on the first and second manual digits. The majority of megaraptorids are known from South America, although a single genus (Australovenator) plus additional indeterminate material is also known from Australia. This clade has a controversial placement among theropods, and recently has been interpreted alternatively as a carcharodontosaurian or a tyrannosauroid lineage. We describe new fragmentary but associated postcranial remains from the opal fields of Lightning Ridge (middle-Albian, Griman Creek Formation) in north-central New South Wales. The new unnamed taxon exhibits a number of unusual features that suggest the presence of a hitherto unrecognized Australian megaraptorid. From an Australian perspective, the Lightning Ridge taxon predates Australovenator by c.10Ma and is minimally coeval with megaraptoran material reported from the Eumeralla Formation of Victoria (but potentially 6.1–9.5 Ma younger). It is also notable as the largest predatory dinosaur yet identified from Australia and is only the second theropod known from more than a single element. A Bayesian phylogenetic approach integrating morphological, stratigraphic and palaeogeographic information tested both the carcharodontosaurian and tyrannosauroid placements for Megaraptora. Regardless of the preferred placement among Tetanurae, rigorous palaeobiogeographic analyses support an Asian origin of Megaraptora in the latest Jurassic (about 150-135 Ma), an Early Cretaceous (about 130-121 Ma) divergence of the Gondwanan lineage leading to Megaraptoridae, and an Australian root for megaraptorid radiation. These results indicate that Australia’s Cretaceous dinosaur fauna did not comprise simply of immigrant taxa but was a source for complex two-way interchange between Australia-Antarctica-South America leading to the evolution of at least one group of apex predatory dinosaurs in Gondwana.

Evidence of Wildfire From Aptian/Albian Cretaceous Brazil

Evidence of palaeo-wildfire from the upper Lower Cretaceous (Serra do Tucano Formation, Aptian–Albian) of Roraima (North Brazil)

Authors:

Scaramuzza dos Santos et al

Abstract:

Wood fossil charcoal is identified from the upper Lower Cretaceous (Serra do Tucano Formation, Aptian–Albian) of Roraima (North Brazil). The presence of charcoal demonstrates the occurrence of Early Cretaceous palaeo-wildfires for the first time in this region and only the third time for the entirety of South America. A gymnospermous taxonomic affinity can be established for the charred woods and a relationship with conifers is likely, thus providing additional evidence for the taxonomic composition of Early Cretaceous floras in this region.

A 4 Celsius Cold Snap in the Aptian/Albian Cretaceous High Arctic

Mid-Cretaceous High Arctic stratigraphy, climate, and Oceanic Anoxic Events

Authors:

Herrie et al

Abstract:

Over the past decades, much research has focused on the mid-Cretaceous greenhouse climate, the formation of widespread organic-rich black shales, and cooling intervals from low- to mid-latitude sections. Data from the High Arctic, however, are limited. In this paper, we present high-resolution geochemical records for an ∼1.8-km-thick sedimentary succession exposed on Axel Heiberg Island in the Canadian Arctic Archipelago at a paleolatitude of ∼71°N. For the first time, we have data constraints for the timing and magnitude of most major Oceanic Anoxic Events (OAEs) in brackish-water (OAE1a) and shelf (OAE1b and OAE2) settings in the mid-Cretaceous High Arctic. These are consistent with carbon-climate perturbations reported from deep-water records of lower latitudes. Glendonite beds are observed in the upper Aptian to lower Albian, covering an interval of ∼6 m.y. between 118 and 112 Ma. Although the formation of glendonites is still under discussion, these well-dated occurrences may support the existence of cool shelf waters in the High Arctic Sverdrup Basin at this time, coeval with recent geochemical data from the subtropical Atlantic indicating a drop in sea-surface temperature of nearly 4 °C.

The Albian/Maastrichtian Cretaceous Vertebrate Fauna of India's Cauvery Basin

Cretaceous vertebrate fauna of the Cauvery Basin, southern India: Palaeodiversity and palaeobiogeographic implications

Author:

Verma

Abstract:

The vertebrate fauna from the late Albian to Maastrichtian succession of the Cauvery Basin, south India has been known since 1845, but it received only scant attention as compared to the vertebrates already known from the Deccan volcanic province of peninsular India. Recent fossil discoveries appear to support the emergence of significantly diverse marine and non-marine vertebrates comprising fishes, frogs, reptiles (ichthyosaurs, plesiosaurs, turtles, crocodiles and dinosaurs) and a mammal from the Cauvery Basin have revived the interest in the fauna of the basin as it has significant implications for understanding the palaeobiogeography of India. The latest Albian to Turonian marine vertebrates such as sharks, ichthyosaurs and plesiosaurs show a wide geographic distribution and marine territory, while sharks are typically cooler water fauna of high palaeolatitudes. The latest Maastrichtian non-marine vertebrates especially turtles, crocodiles, dinosaurs and a mammal are considered to show mixed Gondwanan and Laurasian affinities thus providing new lines of evidence in favour of a latest Cretaceous biotic links between India and the neighbouring continents. An overview of the vertebrate faunal diversity of the Cretaceous sequences of the Cauvery Basin and its palaeobiogeographic considerations are presented.

A Fern Centric Flora From Albian Cretaceous Antarctica

The Albian fern flora of Alexander Island, Antarctica

Authors:

Nagalingum et al

Abstract:

The Albian Alexander Island macrofossil flora from the Antarctic Peninsula preserves a diverse community of liverworts (Marchantiophyta), ferns (Polypodiopsida), Lycopodiales, Equisetales, Cycadales, Ginkgoales, seed-ferns (Bennettitales and Pentoxylales), Coniferales, and the first representatives of angiospermous leaves in Antarctica. Despite the presence of angiosperms in this assemblage, ferns are the most diverse element of the flora and are also ecologically dominant, while angiosperms contribute a smaller component to floristic diversity and have low abundance. Here we describe 11 fern taxa from this assemblage. The fossils are assigned to Cladophlebis, Sphenopteris and two newly created genera. The new genera and species are described under Adiantitophyllum serratum gen. et. sp. nov. and Nunatakia alexanderensis gen. et. sp. nov., and the new species are recognized as Cladophlebis dissecta sp. nov., Cladophlebis drinnanii sp. nov., Cladophlebis macloughlinii sp. nov. and Sphenopteris sinuosa sp. nov. In total, there are 24 fern species known from Alexander Island. In comparison to older floras (Jurassic) there is a greater diversity of ferns, while latest Cretaceous floras preserve significantly fewer fern species and more angiosperms. Possible factors that might account for such high fern diversity are high rainfall or generally humid conditions, regular disturbances by flooding and occasionally fire, and the preservation of a diverse range of fern communities that represent several palaeoenvironments.

Albian Cretaceous Wyoming and Montana had a Diverse Mammal Population

Tribosphenic mammals from the Lower Cretaceous Cloverly Formation of Montana and Wyoming

Authors:

Cifelli et al

Abstract:

We report a diverse assemblage of tribosphenidan mammals from several localities in the Cloverly Formation (Lower Cretaceous, Albian) of Montana and Wyoming. This unit is of historical significance for yielding well-known dinosaurs (e.g., Deinonychus antirrhopus, Tenontosaurus tilletti) and early mammals (e.g., Gobiconodon ostromi, Montanalestes keeblerorum). We provisionally identify 13 taxa (five of which are formally recognized), including Pappotherium pattersoni, a new species of the deltatheroidan Oklatheridium (O. wiblei, sp. nov.), a eutherian (Montanalestes, previously named), and two new basal tribosphenidans (Argaliatherium robustum, gen. et sp. nov., and Carinalestes murensis, gen. et sp. nov.). An unnamed taxon, represented by associated but almost edentulous dentaries, is interpreted to have had four incisors, a single-rooted canine, three premolars, and four molars, indicating that the metatherian tooth formula was established by the Albian. In addition, an indeterminate lower molar fragment preserving twinned talonid cusps and a buccal postcingulid provides the earliest evidence for Marsupialiformes. We also provide a more detailed description of the associated dentaries (holotype) of Montanalestes keeblerorum. The mammalian fauna from the Cloverly Formation shares several taxa with the roughly contemporaneous Trinity Group of Oklahoma and Texas, an observation that also applies to the dinosaur fauna, suggesting some degree of latitudinal homogeneity among described terrestrial vertebrates in this part of the North American Early Cretaceous.