Evidence of Well Mixed PeriTethys Basins in the Late Callovian/Early Kimmeridgian Jurassic Jura Mountains in Poland?

Seawater temperatures and carbon isotope variations in central European basins at the Middle–Late Jurassic transition (Late Callovian–Early Kimmeridgian)

Author:

Wierzbowski

Abstract:

Oxygen and carbon isotope values and elemental ratios of well-preserved belemnite rostra, brachiopod shells and bulk-carbonates from the Upper Callovian–Lower Kimmeridgian of the Polish Jura Chain, Kujawy (Poland) and Swabian Alb (Germany) are investigated to reconstruct environmental conditions and perturbations in the marine carbon cycle. Belemnite δ18O values show relatively constant temperatures (ca. 12 °C) of bottom waters in the Polish Jura Chain basin during a major part of the Late Callovian–Middle Oxfordian, except for a short-term cooling (to ca. 9 °C) at the Callovian–Oxfordian transition. Belemnite and brachiopod δ18O values show a gradual increase in temperature during the Submediterranean Late Oxfordian; the highest temperatures (ca. 16 °C) are calculated for the Submediterranean Oxfordian–Kimmeridgian transition. Belemnite and brachiopod Mg/Ca and Sr/Ca ratios are disregarded as a paleotemperature proxy because of their weak correlation with δ18O values.

The belemnite and brachiopod isotope data confirm that the carbon isotope composition of belemnite rostra is affected by a metabolic effect, which results in a depletion of belemnite calcite in the 13C isotope. Belemnite rostra are considered, nevertheless, as a valuable tracer of temporal variations in the carbon isotope composition of marine carbonates. Belemnite δ13C data show the presence of two positive excursions (in the Upper Callovian and the Middle Oxfordian) in the carbon isotope record of peri-Tethyan carbonates. The excursions are divided by a Lower Oxfordian interval characterized by decreased δ13C values. This is most likely a regional feature caused by upwelling. Lowest belemnite and brachiopod δ13C values are observed in the lower part of the Submediterranean Upper Oxfordian and are linked to a well-mixed state of the seawater in the basins studied. The carbon isotope record of bulk carbonates differs from those of belemnites and brachiopods probably because of strong variations in carbonate production in the Polish Jura Chain basin.

Cuspicephalus scarfi is Really a Wukongopterid Pterosaur From Kimmeridgian Jurassic Britain

The relationships of Cuspicephalus scarfi Martill and Etches, 2013 and Normannognathus wellnhoferi Buffetaut et al., 1998 to other monofenestratan pterosaurs

Authors:

Witton et al

Abstract:

The evolution of pterodactyloid pterosaurs occurred in a ‘modular’ fashion with ‘pterodactyloid’-type crania and cervical vertebrae evolving in pterodactyloid sister taxa – early monofenestratan pterosaurs – before later postcervical modifications marked the development of the true pterodactyloid condition. This means of evolution creates problems for distinguishing isolated pterodactyloid crania from those of non-pterodactyloid monofenestratans, and has led to uncertainty over the affinities of two Late Jurassic European pterosaurs known only from skulls, Cuspicephalus scarfi Martill and Etches, 2013 and Normannognathus wellnhoferi Buffetaut et al., 1998. Some aspects of their cranial anatomy suggest affinities to early pterodactyloids – specifically the Germanodactylidae – while others indicate a relationship with a group of non-pterodactyloid monofenestratans, the Wukongopteridae. Here, we characterise the skulls of Jurassic monofenestratans to provide greater insight into the identity of these pterosaurs. We find a suite of characters indicating that Cuspicephalus is a wukongopterid, notable for being a particularly large and long snouted member of the group, as well as the youngest, and the first European record of this clade. The affinities of Normannognathus are less clear however. We consider its previous allocation to the Germanodactylidae doubtful, and note some similarities it shares with ctenochasmatoid pterodactyloids, but the only known specimen is probably too fragmentary for confident referral to any specific clade within Monofenestrata.

Mark has an awesome post with explanations on our friend here.

Three Oldest Known Snake Fossils Found From Jurassic Bathonian Jurassic Britain, Kimmeridgian Jurassic Portugal

Fossilized remains of four ancient snakes have been dated between 140 and 167 million years old - nearly 70 million years older than the previous record of ancient snake fossils - and are changing the way we think about the origins of snakes, and how and when it happened. The findings have been published in the prestigious peer-reviewed journal Nature Communications.

"The study explores the idea that evolution within the group called 'snakes' is much more complex than previously thought," says lead author and professor Michael Caldwell in the Faculty of Science at the University of Alberta. "Importantly, there is now a significant knowledge gap to be bridged by future research as no fossils snakes are known from between 140 to 100 million years ago."

The oldest known snake, from Southern England, near Kirtlington, Eophis underwoodi, is known only from very fragmentary remains and was a small individual, though it is hard to say how old it was at the time it died. The largest snake, Portugalophis lignites, from coal deposits in Portugal, near Guimarota, was a much bigger individual at nearly a meter or more in length. Several of these ancient snakes (Eophis, Portugalophis and Parviraptor) were living in swampy coastal areas on large island chains in western parts of ancient Europe, while the North American species, Diablophis gilmorei, is found in river deposits from some distance inland in Western Colorado.

This new study makes it clear that the sudden appearance of snakes, some 100 million years ago, reflects a gap in the fossil record, not an explosive radiation of early snakes. From 167 to 100 million years ago, some 70 million years, snakes were radiating and evolving towards the elongate, limb-reduced body plan characterizing the now well known, ~100-90 million year old, marine snakes from the West Bank, Lebanon, and Argentina, that still possess small but well developed rear limbs. As is always the case, the distribution of these newer oldest snakes, and the anatomy of the skull and skeletal elements, makes it clear that even older snake fossils are waiting to be found.

"Based on the new evidence and through comparison to living legless lizards that are not snakes," explains Caldwell, "the paper explores the novel idea that the evolution of the characteristic snake skull and its parts appeared long before snakes lost their legs."

link.

paper link.

The First Pterosaur From Kimmeridgian Jurassic Scotland

A Scottish pterosaur in London: the first record of Pterosauria from the Upper Jurassic (Kimmeridgian) of Eathie (Ross and Cromarty), Scotland

Authors:

Steel et al

Abstract:

A pterosaur wing phalange from the Kimmeridgian of Eathie (Ross and Cromarty) is identified as the first pterosaur to have been collected in Scotland. The specimen was acquired by the British Museum (Natural History) in 1888, but an old collector's label gives the date of collection as 1850. The handwriting matches that of Charles W. Peach (1800–1886), who later became better known for his fossil fish and plant collections, which still exist in the Natural History Museum, London, and other museums. Peach collected this pterosaur specimen during his first year of working in Scotland, and it was probably one of his earliest finds of north of the border. Pterosaur remains are exceptionally rare in Scotland and otherwise unknown from this particular site, so this newly recognised specimen is a significant addition to the Scottish fossil record. It is also among the earliest UK pterosaur finds, post-dating Mary Anning's discovery of Dimorphodon by just over two decades.

Sauropod Niche Partitioning in the Late Jurassic Morrison Formation

How the largest animals to have ever walked the Earth fed, and how this allowed them to live alongside one another in prehistoric ecosystems is the subject of new research from the University of Bristol and the Natural History Museum, London.

The sauropods – large, long-necked plant-eating dinosaurs such as Diplodocus and Brachiosaurus – dominated the land between 210 and 65 million years ago. They were the largest land animals of all time, with the biggest weighing 80 tonnes (more than 11 elephants) and would have needed vast amounts of food.

Despite this, multiple sauropod species often lived alongside each other. The most notable example is the community of the Late Jurassic Morrison Formation, a distinctive sequence of sedimentary rock in the western United States from which over 10 species of sauropod are known.

How so many giant herbivores could have coexisted has long been a mystery: even the highly diverse faunas seen in modern Africa only support one truly gigantic species, the elephant. This is made even more puzzling by the harsh, semi-arid environment of the Morrison Formation during the Jurassic, which would have limited plant growth.

A study conducted by David Button, a PhD student in Bristol's School of Earth Sciences and the Natural History Museum, and colleagues used a novel combination of approaches to investigate this problem.

Although sauropods were gigantic, their heads were comparatively very small and so how they ingested enough food has puzzled many scientists. The researchers focussed on the skull and jaws of sauropods, using a variety of biomechanical techniques to investigate how they functioned and what this would mean for sauropod ecology.

Using CT scans, the researchers digitally reconstructed the skulls of the sauropods Camarasaurus and Diplodocus, along with the jaw and neck muscles of both species from the traces left on the bones where these muscles were attached in life. These two species are very common in the Morrison Formation, and are known to have widely co-existed. From this data, a biomechanical computer model of the skull of Camarasaurus was built using Finite Element Analysis (FEA), a modelling technique often employed in engineering and design to calculate stress and strain distribution in complex shapes. This model was then compared to a pre-existing model of Diplodocus in order to investigate how the dinosaurs fed.

David Button said: "Our results show that although neither could chew, the skulls of both dinosaurs were sophisticated cropping tools. Camarasaurus had a robust skull and strong bite, which would have allowed it to feed on tough leaves and branches. Meanwhile, the weaker bite and more delicate skull of Diplodocus would have restricted it to softer foods like ferns. However, Diplodocus could also have used its strong neck muscles to help it detach plant material through movements of the head. This indicates differences in diet between the two dinosaurs, which would have allowed them to coexist."

The researchers also used a series of biomechanical measurements from other sauropod species to calculate the functional disparity in their skulls and jaws and found that other Morrison Formation sauropods were also highly varied in feeding adaptations, suggesting different diets.

Co-author, Professor Emily Rayfield of the University of Bristol said: "In modern animal communities differences in diet such as this – termed 'dietary niche partitioning' – allow multiple similar species to coexist by reducing competition for food. Although, dietary niche partitioning has been suspected between Morrison Formation sauropods based on their structural features and patterns of tooth-wear, this is the first study to provide strong, numerical, biomechanical evidence for its presence in this fossil community."

link.

paper link.

Eousdryosaurus nanohallucis: A new Dryosaurid Ornithopod From Kimmeridgian Jurassic

A new dryosaurid ornithopod (Dinosauria, Ornithischia) from the Late Jurassic of Portugal

Authors:

Escaso et al

Abstract:

A new dryosaurid ornithopod, Eousdryosaurus nanohallucis, gen. et sp. nov., is described here based on a single specimen from the Late Jurassic Alcobaça Formation of Portugal. Eousdryosaurus nanohallucis is distinguished from all other dryosaurids by eight autapomorphic features and an unique combination of characters, some of which are also shared by other dryosaurids. Eousdryosaurus is linked with Dryosauridae, because the fourth trochanter is proximally placed and widely separated from the scar for the insertion of the M. caudifemoralis longus, which is restricted to the medial surface of the femoral shaft. Phylogenetic analysis nests Eousdryosaurus in an unresolved polytomy at the base of Dryosauridae together with Callovosaurus, Dryosaurus, and Kangnasaurus. The complete pes of Eousdryosaurus, which has a phalangeal formula of 1-3-4-5-0, supports the putative autapomorphic reduction of the dryosaurid pes that also occurs in parallel in more derived ornithopods.

Colymbosaurus megadeirus: A Reassessment of Kimmeridgian Jurassic Plesiosaur Paleodiversity

Anatomy of Colymbosaurus megadeirus (Reptilia, Plesiosauria) from the Kimmeridge Clay Formation of the U.K., and high diversity among Late Jurassic plesiosauroids

Authors:

Benson et al

Abstract:

We describe the syntype postcranial skeletons of the cryptoclidid plesiosauroid Colymbosaurus megadeirus. C. megadeirus is the type species of Colymbosaurus, and one other valid species, C. svalbardensis, is known. Although it is in widespread usage, C. trochanterius is a not valid species, although the presence of an anteroposteriorly oriented ridge bisecting the distal surfaces of the holotype humerus allows its referral to Colymbosaurus sp. Some specimens previously referred to C. trochanterius, including the holotype of ‘Plesiosaurus’ manselii, lack this feature, or show other differences from our hypodigm, suggesting that they are taxonomically distinct from Colymbosaurus, and countering previous suggestions that the Kimmeridge Clay Formation represents a depauperate plesiosauroid fauna. Substantial differences between the atlas-axis complexes and cervical vertebrae of Kimmerosaurus langhami, ‘Plesiosaurus’ manselii, C. megadeirus, and specimens referred here to cf. Spitrasaurus indicate that at least four plesiosauroid taxa were present in the Kimmeridge Clay Formation. This proposition is also supported by coracoid morphotypes, and demonstrates that Late Jurassic plesiosauroids were taxonomically diverse. Most Late Jurassic–Early Cretaceous cryptoclidids belong to a monophyletic Colymbosaurinae, but Kimmerosaurus and its sister taxon Tatenectes originated independently from Middle Jurassic cryptoclidids.

Modeling the Feeding Biomechanics of a Kimmridgian Jurassic Pliosaur

Functional anatomy and feeding biomechanics of a giant Upper Jurassic pliosaur (Reptilia: Sauropterygia) from Weymouth Bay, Dorset, UK

Authors:

Foffa et al

Abstract:

Pliosaurs were among the largest predators in Mesozoic seas, and yet their functional anatomy and feeding biomechanics are poorly understood. A new, well-preserved pliosaur from the Kimmeridgian of Weymouth Bay (UK) revealed cranial adaptations related to feeding. Digital modelling of computed tomography scans allowed reconstruction of missing, distorted regions of the skull and of the adductor musculature, which indicated high bite forces. Size-corrected beam theory modelling showed that the snout was poorly optimised against bending and torsional stresses compared with other aquatic and terrestrial predators, suggesting that pliosaurs did not twist or shake their prey during feeding and that seizing was better performed with post-symphyseal bites. Finite element analysis identified biting-induced stress patterns in both the rostrum and lower jaws, highlighting weak areas in the rostral maxillary-premaxillary contact and the caudal mandibular symphysis. A comparatively weak skull coupled with musculature that was able to produce high forces, is explained as a trade-off between agility, hydrodynamics and strength. In the Kimmeridgian ecosystem, we conclude that Late Jurassic pliosaurs were generalist predators at the top of the food chain, able to prey on reptiles and fishes up to half their own length.

Surprise! Upper Jurassic Morrison Formation had Conifer Forests

Greater palaeobiodiversity in conifer seed cones in the Upper Jurassic Morrison Formation of Utah, USA

Authors:

Gee et al

Abstract:

Although fossil conifer wood, leaves, and pollen have been known from the Upper Jurassic Morrison Formation of the Western Interior of North America for many decades, only a few conifer seed cones have been described as carbonaceous compressions and casts with little internal structure. Recently, however, over 60 silicified seed cones with preserved internal anatomy were amassed by collectors from 11 localities in northeastern and southern Utah and brought to the attention of palaeobotanists. Here we describe the silicified cones from Utah and compare them to one another in size, gross morphology and internal construction. The fossil material is sorted into five new morphotypes of seed cone. Morphotype 1 pertains to Araucariaceae, Morphotype 2 is most likely Pinaceae, and Morphotype 5 is Cheirolepidiaceae. The familial affinity of Morphotypes 3 and 4 cannot be determined at this time. Comparative size analysis based on volume calculations shows that Morphotypes 2, 3, 4 and 5 are extremely small, smaller than any Mesozoic araucarian seed cone, and that Morphotype 1 falls within the range of small fossil araucarian cones. Most cone-bearing localities are situated to the northwest, west, and south of Hanksville in southcentral Utah. With regard to palaeobiodiversity, if Araucaria delevoryasii Gee from Wyoming is included, there are now six morphotypes of seed cones that represent at least three conifer families in Utah and Wyoming. Because many conifers are arborescent and form forests, the new fossil evidence suggests that species-diverse conifer forests or woodlands were a major type of vegetation in the Morrison Formation during the Late Jurassic.

Oldest Record of Azhdarchid Pterosaurs in Africa From Kimmeridgian/Tithonian Jurassic Tanzania

New pterosaur material from the Upper Jurassic of Tendaguru (Tanzania), Africa

Authors:

Costa et al

Abstract:

The pterosaur fossil record from Africa is exceedingly scarce and one of the least known for any continental land mass. The specimens here described are housed at the Naturkundemuseum of the Humboldt University and consist of two cervical vertebrae, a coracoid and a wing metacarpal recovered from the Upper Jurassic Tendaguru Formation, Tanzania. Due to the general morphology and the absence of a lateral pneumatic foramen in both vertebrae, as well as the presence of a longitudinal depression, not previously reported in pterosaurs, we consider these specimens as representatives of a new species of Azhdarchidae. Moreover, because the coracoid, which bears three well-developed pneumatic foramina, has a well-excavated depression that is medially positioned at the posterior face of the acrocoracoid process, we regard this as a new basal pterodactyloid species. The wing metacarpal is greatly elongated and clearly belongs to Pterodactyloidea. Its elongation and slender aspect, as well as the sub-triangular shape of its proximal articular end, likely place it within the Tapejaroidea. The material here described shows the potential of these deposits to provide more informative pterosaur material and provisionally extends the oldest record of azhdarchids to the Kimmeridgian–Tithonian of Africa.

Docodon apoxys: A New Docodon Species From Oxfordian/Kimmeridgian/Tithonian Jurassic Colorado

A New Species of Docodon (Mammaliaformes: Docodonta) from the Upper Jurassic Morrison Formation and a Reassessment of Selected Craniodental Characters in Basal Mammaliaforms

Authors:

Rougier et al

Abstract:

We describe a new species of the basal mammaliaform Docodon, D. apoxys, sp. nov., represented by three nearly complete dentaries from the Upper Jurassic Morrison Formation of central Colorado. This species differs from other known species of Docodon in the relative heights of the principal molar cusps and in the size of the distal molars. In addition, we attribute a partial rostrum preserving much of the maxilla and most of the premaxilla, bearing a complete incisor and premolar count, to Docodon sp. These materials supply previously unknown morphology for this classic North American Jurassic taxon, and help establish a common morphology for Docodonta as a whole. While Docodon differs from the Portuguese docodont Haldanodon in the presence of only five upper incisors (none of which is entirely within the maxilla), an internarial bar is present in both taxa. The new specimens also unambiguously preserve a complete and undistorted angular process that differs conspicuously from the classical interpretation of the holotype of Docodon victor; this structure in docodonts closely resembles the angular process in australosphenidans and trechnotheres. We abandon the concept of a “pseudangular” process and we consider the angular process to be a homologous feature (where present) across Mammaliaformes.

A Kimmeridgian Jurassic Pliosaur Appears to Have had a Shark-like Sensory System

Complex rostral neurovascular system in a giant pliosaur

Authors:

Foffa et al

Abstract:

Pliosaurs were a long-lived, ubiquitous group of Mesozoic marine predators attaining large body sizes (up to 12 m). Despite much being known about their ecology and behaviour, the mechanisms they adopted for prey detection have been poorly investigated and represent a mystery to date. Complex neurovascular systems in many vertebrate rostra have evolved for prey detection. However, information on the occurrence of such systems in fossil taxa is extremely limited because of poor preservation potential. The neurovascular complex from the snout of an exceptionally well-preserved pliosaur from the Kimmeridgian (Late Jurassic, c. 170 Myr ago) of Weymouth Bay (Dorset, UK) is described here for the first time. Using computed tomography (CT) scans, the extensive bifurcating neurovascular channels could be traced through the rostrum to both the teeth and the foramina on the dorsal and lateral surface of the snout. The structures on the surface of the skull and the high concentrations of peripheral rami suggest that this could be a sensory system, perhaps similar to crocodile pressure receptors or shark electroreceptors.

Torvosaurus gurneyi the Largest Land Predator of Kimmeridgian-Tithonian Jurassic Europe

Torvosaurus gurneyi n. sp., the Largest Terrestrial Predator from Europe, and a Proposed Terminology of the Maxilla Anatomy in Nonavian Theropods

Authors:

Hendrickx et al

Abstract:

The Lourinhã Formation (Kimmeridgian-Tithonian) of Central West Portugal is well known for its diversified dinosaur fauna similar to that of the Morrison Formation of North America; both areas share dinosaur taxa including the top predator Torvosaurus, reported in Portugal. The material assigned to the Portuguese T. tanneri, consisting of a right maxilla and an incomplete caudal centrum, was briefly described in the literature and a thorough description of these bones is here given for the first time. A comparison with material referred to Torvosaurus tanneri allows us to highlight some important differences justifying the creation of a distinct Eastern species. Torvosaurus gurneyi n. sp. displays two autapomorphies among Megalosauroidea, a maxilla possessing fewer than eleven teeth and an interdental wall nearly coincidental with the lateral wall of the maxillary body. In addition, it differs from T. tanneri by a reduced number of maxillary teeth, the absence of interdental plates terminating ventrally by broad V-shaped points and falling short relative to the lateral maxillary wall, and the absence of a protuberant ridge on the anterior part of the medial shelf, posterior to the anteromedial process. T. gurneyi is the largest theropod from the Lourinhã Formation of Portugal and the largest land predator discovered in Europe hitherto. This taxon supports the mechanism of vicariance that occurred in the Iberian Meseta during the Late Jurassic when the proto-Atlantic was already well formed. A fragment of maxilla from the Lourinhã Formation referred to Torvosaurus sp. is ascribed to this new species, and several other bones, including a femur, a tibia and embryonic material all from the Kimmeridgian-Tithonian of Portugal, are tentatively assigned to T. gurneyi. A standard terminology and notation of the theropod maxilla is also proposed and a record of the Torvosaurus material from Portugal is given.

Kimmeridgian/Tithonian Jurassic Sauropod Lourinhasaurus is Really a Camarasaur

Phylogenetic reassessment of Lourinhasaurus alenquerensis, a basal Macronaria (Sauropoda) from the Upper Jurassic of Portugal

Authors:

Mocho et al

Abstract:

Lourinhasaurus alenquerensis is a Portuguese Upper Jurassic dinosaur whose lectotype is one of the most complete sauropod specimens from the Portuguese fossil record and from the Upper Jurassic of Europe. It was recovered from sediments of the Sobral Formation (upper Kimmeridgian to lower Tithonian) at Moinho do Carmo (Alenquer, Portugal). The lectotype of Lourinhasaurus was first related to Apatosaurus and then tentatively related to Camarasaurus. Finally, it was established as a new taxon, Lourinhasaurus, including the Moinho do Carmo specimen. At the time of writing, Lourinhasaurus had a poor diagnosis and an unstable phylogenetic position. Revision of the Moinho do Carmo specimen has led to a detailed description and a new and more complete codification for several morphological characters. The phylogenetic analyses proposed herein considered Lourinhasaurus as a Camarasauromorpha Macronaria. This study also recovered a Camarasauridae clade incorporating Lourinhasaurus, Camarasaurus and, putatively, Tehuelchesaurus and that implies the presence of Camarasauridae in the European Upper Jurassic. Besides the strong similarity to Camarasaurus, Lourinhasaurus alenquerensis is here considered a valid taxon with 13 putative autapomorphies such as a sagittal keel on the dorsal margin of sacral neural spines, circular and deep spinoprezygapophyseal fossa on proximal caudal vertebrae, marked crest and groove bordering the lateral margin of the acetabulum in the ischium, and a marked deflection of the entire femoral shaft without lateral bulge. The apparently high number of taxa among the sauropod fauna from the Iberian Peninsula during the Late Jurassic is similar to the palaeobiodiversity recorded in formations of the same age, i.e. Morrison and Tendaguru, and does not support the hypothesis of a connection between the North America and Iberian Peninsula faunas during the later part of the Late Jurassic reflected by other faunal and floral groups.

Kimmeridgian Jurassic Postcranial Mammal Fossils From Portugal

Mammalian postcranial bones from the Late Jurassic of Portugal and their implications for forelimb evolution

Author:

Thomas Martin

Abstract:

Isolated bones of forelimb and pelvic girdle (two humeri, five ulnae, and an ilium) recovered from the Late Jurassic (Kimmeridgian) Guimarota coal mine in western central Portugal are attributed to the docodont Haldanodon exspectatus, dryolestoids, and a ?paulchoffatiid multituberculate. The larger of the two humeri is assigned to the dryolestid Dryolestes leiriensis based on size and shape. It clearly exhibits an incipient trochlea at the distal joint, suggesting that this derived character was well established among Late Jurassic dryolestidans, including Henkelotherium. Plesiomorphic characters are the prominent spherical radial condyle and the weakly developed ulnar condyle. An incipient medial keel is present in distal aspect of the humerus trochlea. The shallow olecranon fossa of the humerus corresponds to the small anconeal process of the radius. The smaller humerus with damaged distal joint is 50% smaller and cannot be assigned to a specific dryolestoid taxon. It is in the size range of the smaller Guimarota dryolestoids Krebsotherium, Drescheratherium, and Henkelotherium. One ulna differs from the dryolestoid ulnar shape by the nearly semicircular articular surface for the ulnar condyle of the humerus, the asymmetric olecranon with medial overhang, as well as the prominent anconeal process and is tentatively attributed to a paulchoffatiid multituberculate.

Aurornis xui: Feathered Relative of Early Birds, Proves Feathers Before Flight

Feathered dinosaurs used to be as valuable as gold dust. Now, so many specimens have been unearthed that museums are overflowing. But for all the specimens, a crucial question has remained unanswered: which species was the original ancestor of birds?

A new species found in China has shed light on the answer. The two-foot long Aurornis xui, the “daybreak bird,” fleshes out the relationships between bird-like dinosaurs and, along with its cousin species Archaeopteryx and Anchiornis, restores its lineage as the likely predecessors of birds.

The early relationships of a group called Avialae, the dinosaur line leading directly to modern birds, have been a hot point of debate. Over the last few years, with new bird-like dinosaur discoveries, some palaeontologists have even removed the iconic Archaeopteryx and its relatives from the Avialae group altogether. However, this shift would have meant that powered flight evolved multiple times in feathered dinosaurs, a less likely situation than one such adaptation.

Now, Aurornis xui, named in honor of dinosaur hunter Xu Xing, appears to have settled that part of the debate. Along with Anchiornis of the same age (about 155-160 million years), and Archaeopteryx (150 million years), Aurornis fits within the earliest ancestry of Avialae. The existence of three contemporary species allowed researchers to triangulate their relationships based on their appearance. Archaeopteryx was knocked off its perch as the oldest bird back in 2009 by Anchiornis, and now Aurornis has finished the dethroning, with the three species together sitting at the very base of the Avialae lineage that would later give rise to all other birds.

For a moment when I saw the reconstruction, I thought the chickensaurus project was successful!

New Study of Dysalotosaurus Brains and Ears Sheds Light on Dinosaur Maturation

A new study conducted at the University of Bristol and published online today in the Journal of Evolutionary Biology sheds light on how the brain and inner ear developed in dinosaurs.

Stephan Lautenschlager from Bristol's School of Earth Sciences, together with Tom Hübner from the Niedersächsische Landesmuseum in Hannover, Germany, picked the brains of 150 million year old dinosaurs.

The two palaeontologists studied different fossils of the Jurassic dinosaur Dysalotosaurus lettowvorbecki: a very young (juvenile) individual of approximately three years of age and a fully grown specimen of more than 12 years of age.

Stephan Lautenschlager, lead author of the paper, said: "The two different growth stages of Dysalotosaurus provided a unique opportunity to study their brain, and how it developed during the growth of the animal."

Using high-resolution CT scanning and 3D computer imaging, it was possible to reconstruct and visualise the brain and inner ear of Dysalotosaurus lettowvorbecki – a small, plant-eating dinosaur, which lived 150 million years ago, in what is now Tanzania.

Co-author Tom Hübner said: "Well-preserved fossil material, which can be used to reconstruct the brain anatomy is usually rare. Thus, we were fortunate to have different growth stages available for our study."

By looking at the brain and inner ear anatomy, the two researchers found that the brain of Dysalotosaurus underwent considerable changes during growth – most likely as a response to environmental and metabolic requirements. However, important parts responsible for the sense of hearing and cognitive processes were already well developed in the young individual.

Stephan Lautenschlager said: "Our study shows that the brain was already well-developed in the young dinosaurs and adapted perfectly to interact with their environment and other individuals."

This study has important ramifications for the understanding of how parts of the brain developed in dinosaurs. However, further research into that field is necessary to investigate if the pattern of brain development in individual dinosaurs is also reflected in a large scale trend during the more than 150 million years of dinosaur evolution.

Kimmeridge Clay Jurassic Organic Deposits Due to 'Burn Down' Events

The sediments of the Kimmeridge Clay Formation were deposited during the Late Jurassic between around 160 and 145 million years ago, the age of the reptiles. They are the main oil source rock in the North Sea. However, within this unit beds rich in organic matter are interspersed with organic-poor sediments. New evidence demonstrates that organic-poor sediments were probably caused by post-depositional loss of organic matter during so-called 'burn-down' events.

The Kimmeridge Clay Formation is named after the English village of Kimmeridge on Dorset's 'Jurassic Coast', a favourite haunt of fossil hunters. The sediments comprising the formation, which is particularly well exposed here, were probably deposited in shallow marine environment with an average water depth of 50-100 metres.

"We were particularly interested in the transition between organic-rich and organic-poor sediments," said Dr Ian Harding of the University of Southampton's School of Ocean and Earth Science at the National Oceanography Centre, Southampton (NOCS), and a member of the team that investigated the underlying processes.

A long-held hypothesis is that the organic-rich beds were the result of elevated planktonic productivity in sunlit surface waters, possibly accentuated by enhanced preservation of the resulting organic matter by the oxygen-depleted bottom waters resulting from this excess productivity.

A second possibility was that a cyclic rise and fall of the interface between oxygenated and oxygen-depleted waters was responsible for the transition between organic-rich and organic poor sediments. According to this theory, when oxygenated waters reached the seabed, organic matter already deposited would have been oxidised and degraded. These post-depositional 'burn down' events could have alternated with periods during which the bottom waters had little oxygen, favouring preservation of organic matter.

"The first theory emphasises changes in the amount of organic matter reaching the seabed, while the 'burn-down' theory puts more weight on the relative dominance of preservation or degradation after it has got there," said Dr Harding.

To distinguish between these two theories, he and colleagues from the University of Bremen and the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, analysed the chemical composition and organic content of a sediment core from a borehole in Swanworth Quarry in Dorset, originally drilled as part of the Natural Environment Research Council (NERC) Rapid Global Geological Events Project run by NOCS' Prof. John Marshall.

Monika Kodrans-Nsiah, a PhD student jointly supervised by Dr Harding and Dr Karin Zonneveld (Bremen) was responsible for analysing the fossilised organic cysts of various species of dinoflagellate, a group of tiny aquatic organisms, found in the sediments. Different dinoflagellate species are known to be adapted to different environmental conditions, so studying the distribution of 'dinocyst' fossils helps reconstruct past environments.

The lower part of the core was rich in organic carbon, with abundant dinocysts, and its chemical composition was indicative of anoxic conditions, implying that sediments were deposited and preserved in an oxygen-deficient environment.

However, the chemical composition of the uppermost sediments indicated the presence of oxygenated water when they were deposited. This transition was sudden, occurring at a drilling depth of 122.37 metres, but changes in organic content and dinocyst distributions were more gradual.

"It looks likely that influxes of well-oxygenated bottom water caused the oxidation and degradation of organic matter and cysts after they were deposited," said Dr Harding: "This would explain the gradual reduction in the amount of organic matter above the transition, and provide support for the idea of 'burn-down' events during the Jurassic."

So, am I reading this right? This is not caused by eutrophication?