Hualianceratops wucaiwanensis: a new Basal Ceratopsian from Oxfordian Jurassic China

A New Taxon of Basal Ceratopsian from China and the Early Evolution of Ceratopsia

Authors:

Han et al

Abstract:

Ceratopsia is one of the best studied herbivorous ornithischian clades, but the early evolution of Ceratopsia, including the placement of Psittacosaurus, is still controversial and unclear. Here, we report a second basal ceratopsian, Hualianceratops wucaiwanensis gen. et sp. nov., from the Upper Jurassic (Oxfordian) Shishugou Formation of the Junggar Basin, northwestern China. This new taxon is characterized by a prominent caudodorsal process on the subtemporal ramus of the jugal, a robust quadrate with an expansive quadratojugal facet, a prominent notch near the ventral region of the quadrate, a deep and short dentary, and strongly rugose texturing on the lateral surface of the dentary. Hualianceratops shares several derived characters with both Psittacosaurus and the basal ceratopsians Yinlong, Chaoyangsaurus, and Xuanhuaceratops. A new comprehensive phylogeny of ceratopsians weakly supports both Yinlong and Hualianceratops as chaoyangsaurids (along with Chaoyangsaurus and Xuanhuaceratops), as well as the monophyly of Chaoyangosauridae + Psittacosaurus. This analysis also weakly supports the novel hypothesis that Chaoyangsauridae + Psittacosaurus is the sister group to the rest of Neoceratopsia, suggesting a basal split between these clades before the Late Jurassic. This phylogeny and the earliest Late Jurassic age of Yinlong and Hualianceratops imply that at least five ceratopsian lineages (Yinlong, Hualianceratops, Chaoyangsaurus + Xuanhuaceratops, Psittacosaurus, Neoceratopsia) were present at the beginning of the Late Jurassic.

Yi qi: The Bizzaro World Feathered *AND* Bat Winged Freak, ahem, Scansoriopterygid Maniraptor Theropod From Callovian/Oxfordian Jurassic China

A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings

Authors:

Xu et al

Abstract:

The wings of birds and their closest theropod relatives share a uniform fundamental architecture, with pinnate flight feathers as the key component. Here we report a new scansoriopterygid theropod, Yi qi gen. et sp. nov., based on a new specimen from the Middle–Upper Jurassic period Tiaojishan Formation of Hebei Province, China. Yi is nested phylogenetically among winged theropods but has large stiff filamentous feathers of an unusual type on both the forelimb and hindlimb. However, the filamentous feathers of Yi resemble pinnate feathers in bearing morphologically diverse melanosomes. Most surprisingly, Yi has a long rod-like bone extending from each wrist, and patches of membranous tissue preserved between the rod-like bones and the manual digits. Analogous features are unknown in any dinosaur but occur in various flying and gliding tetrapods, suggesting the intriguing possibility that Yi had membranous aerodynamic surfaces totally different from the archetypal feathered wings of birds and their closest relatives. Documentation of the unique forelimbs of Yi greatly increases the morphological disparity known to exist among dinosaurs, and highlights the extraordinary breadth and richness of the evolutionary experimentation that took place close to the origin of birds.

Studying Arboroharamiya Suggests Haramiyidans Closely Related to Multituberculates

Dental and Mandibular Morphologies of Arboroharamiya (Haramiyida, Mammalia): A Comparison with Other Haramiyidans and Megaconus and Implications for Mammalian Evolution

Authors:

Meng et al

Abstract:

Background

Two recent studies published in the same issue of Nature reached conflicting conclusions regarding the phylogeny of early mammals: One places the clade containing haramiyidans and multituberculates within the Mammalia and the other separates haramiyidans from multituberculates and places the former outside of the Mammalia. These two contrasting results require that the minimally oldest divergence time of the Mammalia was within the Late Triassic or the Middle Jurassic, respectively. Morphological descriptions of the species named in the two papers were brief, and no comparisons between the newly named species were possible.

Principal Findings

Here we present a detailed description of the dentary bone, teeth, occlusal and wear patterns of the haramiyidan Arboroharamiya and compare it with other haramiyidans and Megaconus. Using this new information, we suggest that tooth identifications and orientations of several previously described haramiyidan species are incorrect, and that previous interpretations of haramiyidan occlusal pattern are problematic. We propose that the published upper tooth orientation of Megaconus was problematic and question the number of upper molars, the length of dentition and mandible, and presence of the mandibular middle ear in Megaconus.

Conclusions

The additional morphological descriptions and comparisons presented here further support the view that Arboroharamiya, as a derived haramiyidan, shows similarity to multituberculates in tooth and mandible morphologies. Our comparison also suggests that Megaconus lacks many diagnostic features for the family Eleutherodontidae and that its close affinity with multituberculates cannot be ruled out. The detailed morphological data demonstrate that haramiyidans are more similar to multituberculates than to any other mammaliaforms.

Palaeobiogeography of the Bajocian/Oxfordian Jurassic Sinai

Palaeobiogeography of the Bajocian–Oxfordian macrofauna of Gebel Maghara (North Sinai, Egypt): Implications for eustacy and basin topography

Authors:

Abdelhady et al

Abstract:

Based on newly collected material from the Bajocian–Oxfordian rocks of Gebel Maghara (North Sinai, Egypt) and available published information, the palaeobiogeographic pattern and the dispersal potential of the macrofauna including bivalves, ammonites, corals, and brachiopods are investigated. Both clustering methods and ordination techniques were applied and evaluated. During Bajocian times, G. Maghara occupied an intracratonic setting and was isolated from the main ocean by islands and shallows. These barriers may have limited the dispersal potential of the macrofauna and impeded the faunal exchange with even nearby areas. Although these barriers had disappeared by rejuvenation of faults during an active rift stage in Bathonian times, the same biogeographic patterns continued, which may be related to the global sea level lowstand. By Callovian times, a time of global sea level highstand, in contrast, the fauna of the study area became very similar to that of northeastern Africa. Similarly, diversity and extinction rates increased from the middle Bathonian onward, which may reflect intrusion of cosmopolitan taxa due to the newly established open marine setting and the global sea level highstand. Towards the Oxfordian, lowering of temperature may have limited the dispersal ranges of the macrofauna within the Ethiopian Province. As a result, a southeastern subprovince (Indo–Malagasy) including Tanzania, Madagascar, and India became established. Although the geographic patterns of the different faunal groups exhibit some similarities resulting from abiotic factors such as sea level, climate, and basin topography, biotic characteristics such as life habits and larval development played the dominant role in shaping the distribution pattern. The dispersal potential was highest for ammonites, followed by that of corals and then bivalves. Brachiopods had the lowest dispersal potential.

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.

Chinese Oxfordian Jurassic Euharamiyidan Mammals Suggest Allotheria Split From Other Mammals at the Rhaetian/Norian Triassic Boundary

Three new Jurassic euharamiyidan species reinforce early divergence of mammals

Authors:

Bi et al

Abstract:

The phylogeny of Allotheria, including Multituberculata and Haramiyida, remains unsolved and has generated contentious views on the origin and earliest evolution of mammals. Here we report three new species of a new clade, Euharamiyida, based on six well-preserved fossils from the Jurassic period of China. These fossils reveal many craniodental and postcranial features of euharamiyidans and clarify several ambiguous structures that are currently the topic of debate. Our phylogenetic analyses recognize Euharamiyida as the sister group of Multituberculata, and place Allotheria within the Mammalia. The phylogeny suggests that allotherian mammals evolved from a Late Triassic (approximately 208 million years ago) Haramiyavia-like ancestor and diversified into euharamiyidans and multituberculates with a cosmopolitan distribution, implying homologous acquisition of many craniodental and postcranial features in the two groups. Our findings also favour a Late Triassic origin of mammals in Laurasia and two independent detachment events of the middle ear bones during mammalian evolution.

The Paleoenvironment of Northwest Oxfordian Juassic Spain

Timing of sea level, tectonics and climate events during the uppermost Oxfordian (Planula zone) on the Iberian ramp (northeast Spain)

Authors:

Colombie et al

Abstract:

The middle Oxfordian warming climate and sea-level rise initiated the development of vast carbonate platforms in some western European basins. At the same time, however, siliciclastics and siliceous sponges dominated certain marginal areas of the Iberian ramp. There, siliciclastic input was particularly prominent during the latest Oxfordian and may have been related to a global sea-level fall, synsedimentary tectonic activity, or humid climatic conditions in the hinterland. Field analyses and computer modelling have been previously used to determine the factors that controlled sedimentation. However, it is still unclear if the specific conditions that prevailed during the latest Oxfordian were due to eustasy, tectonics or climate, and when precisely they occurred. Here, we document major changes in sedimentological, micropalaeontological, and mineralogical records on the Iberian ramp during this interval. Detailed sedimentary facies and palynofacies analyses combined with sequence-stratigraphic and cyclostratigraphic analyses of the Ricla Barranco section enable the establishment of a high-resolution time frame. Based on the quartz and mica percentage fluctuations, one large- and seven small-scale sequences are defined. The large-scale sequence boundaries correlate with third-order sequence boundaries Ox 8 and Kim 1 defined by Hardenbol et al. (1998). The large-scale maximum-flooding surface corresponds to the base of the most calcareous interval and to the maximum abundance of marine phytoplankton and opaque, equidimensional phytoclasts. The small-scale sequences correspond to the 100-kyr orbital eccentricity cycle. Calcareous nannofossils and clay minerals were used as palaeoclimatic proxies. Nannofossil abundances and fluxes are lower in the upper part than in the lower part of the interval studied, suggesting a decrease in sea-surface trophic conditions, also shown by an increase in the relative abundance of oligotrophic taxa. This upper part is also characterised by an increase in smectite, which coincides with the base of the large-scale highstand deposit, and is interpreted as reflecting the establishment of dry conditions. A first increase in smectite occurs in the lower part of the succession, and coincides with high percentages of quartz and mica. This latter mineralogical assemblage is interpreted as recording the onset of the Late Jurassic to Early Cretaceous rifting stage, which occurred just before the Planula–Galar ammonite subzone transition. The present study points out a return toward optimum conditions for carbonate sedimentation only 300 kyr after the prominent increase in siliciclastic input due to tectonic activity. The recovery of carbonate production was accompanied by a global sea-level rise and by decreasing rainfall on nearby land.

How Oxfordian Jurassic Mammal Dryolestes Chewed

Function of pretribosphenic and tribosphenic mammalian molars inferred from 3D animation

Authors:

Schultz et al

Abstract:

Appearance of the tribosphenic molar in the Late Jurassic (160 Ma) is a crucial innovation for food processing in mammalian evolution. This molar type is characterized by a protocone, a talonid basin and a two-phased chewing cycle, all of which are apomorphic. In this functional study on the teeth of Late Jurassic Dryolestes leiriensis and the living marsupial Monodelphis domestica, we demonstrate that pretribosphenic and tribosphenic molars show fundamental differences of food reduction strategies, representing a shift in dental function during the transition of tribosphenic mammals. By using the Occlusal Fingerprint Analyser (OFA), we simulated the chewing motions of the pretribosphenic Dryolestes that represents an evolutionary precursor condition to such tribosphenic mammals as Monodelphis. Animation of chewing path and detection of collisional contacts between virtual models of teeth suggests that Dryolestes differs from the classical two-phased chewing movement of tribosphenidans, due to the narrowing of the interdental space in cervical (crown–root transition) direction, the inclination angle of the hypoflexid groove, and the unicuspid talonid. The pretribosphenic chewing cycle is equivalent to phase I of the tribosphenic chewing cycle, but the former lacks phase II of the tribosphenic chewing. The new approach can analyze the chewing cycle of the jaw by using polygonal 3D models of tooth surfaces, in a way that is complementary to the electromyography and strain gauge studies of muscle function of living animals. The technique allows alignment and scaling of isolated fossil teeth and utilizes the wear facet orientation and striation of the teeth to reconstruct the chewing path of extinct mammals.

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.

Jianchangnathus robustus: a new Articulated Pterosaur Fossil From Oxfordian Jurassic China

Cranial morphology of a Scaphognathus-like pterosaur, Jianchangnathus robustus, based on a new fossil from the Tiaojishan Formation of western Liaoning, China

Author:

Zhou

Abstract:

A new pterosaur fossil with an articulated skull and fragmentary postcranial skeleton was collected from the Jurassic Tiaojishan Formation of Linglongta, western Liaoning, China. Its configuration shows an affinity with the Scaphognathus-like Jianchangnathus robustus, which was reported from the same region and horizon. The fossil reveals new cranial morphology: a convex dorsal margin of the skull, antorbital fenestra completely posterior to the naris, a long maxillary process and short quadratojugal process of the jugal, and jaw articulation above the midheight of the mandible; the first upper tooth close to the snout tip, the two anterior-most upper teeth tightly arranged, and the fifth upper tooth positioned at the level of the anterior margin of the naris. Recent discoveries of non-pterodactyloids from the Tiaojishan Formation of northeastern China exhibit a high taxonomic diversity comparable to those in the Solnhofen Limestone. Therefore, as a significant pterosaur assemblage before the Solnhofen Limestone, the Tiaojishan Formation provides a new perspective in understanding the evolution and diversity of the non-pterodactyloids.

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.

Kryptodrakon progenitor: A New Pterodactyloid From Oxfordian Jurassic China

The Earliest Pterodactyloid and the Origin of the Group

Authors:

Andres et al

Abstract:

The pterosaurs were a diverse group of Mesozoic flying reptiles that underwent a body plan reorganization, adaptive radiation, and replacement of earlier forms midway through their long history, resulting in the origin of the Pterodactyloidea, a highly specialized clade containing the largest flying organisms. The sudden appearance and large suite of morphological features of this group were suggested to be the result of it originating in terrestrial environments, where the pterosaur fossil record has traditionally been poor [1 and 2], and its many features suggested to be adaptations to those environments [1 and 2]. However, little evidence has been available to test this hypothesis, and it has not been supported by previous phylogenies or early pterodactyloid discoveries. We report here the earliest pterosaur with the diagnostic elongate metacarpus of the Pterodactyloidea, Kryptodrakon progenitor, gen. et sp. nov., from the terrestrial Middle-Upper Jurassic boundary of Northwest China. Phylogenetic analysis confirms this species as the basalmost pterodactyloid and reconstructs a terrestrial origin and a predominantly terrestrial history for the Pterodactyloidea. Phylogenetic comparative methods support this reconstruction by means of a significant correlation between wing shape and environment also found in modern flying vertebrates, indicating that pterosaurs lived in or were at least adapted to the environments in which they were preserved.

Daohugou Biota From a Lagerstatte of Jurassic China is Distinct From the Jehol Biota

The vertebrates of the Jurassic Daohugou Biota of northeastern China

Authors:

Sullivan et al

Abstract:

The Early Cretaceous Jehol Biota of northeastern China has become famous over the last two decades as a source of feathered avialan and non-avialan theropods, preserved alongside an array of other fossil vertebrates, invertebrates, and plants. Still more recently, a rich assemblage referred to in this paper as the Daohugou Biota has begun to emerge from Jurassic strata in the same region. Like their counterparts from the Jehol Biota, Daohugou Biota vertebrate specimens are typically preserved in fine-grained lacustrine beds and often retain feathers and other soft-tissue features. At present, 30 vertebrate taxa (five salamanders, one anuran, two lizards, 13 pterosaurs, five dinosaurs, and four mammals) are known from the Daohugou Biota, which was first recognized at the Daohugou locality in Inner Mongolia. The presence of the salamander Chunerpeton tianyiensis, proposed in this paper as an index fossil for the Daohugou Biota, links the Daohugou locality to five other fossil-producing areas in the provinces of Hebei and Liaoning. The strata containing the Daohugou Biota are close to the Middle–Upper Jurassic boundary and belong at least partly to the regionally widespread Tiaojishan Formation. In general, the vertebrate fauna of the Daohugou Biota is strikingly different from that of the Jehol Biota, although paravian dinosaurs, anurognathid pterosaurs, and salamanders with cryptobranchid and hynobiid affinities occur in both. Nevertheless, the Daohugou Biota and the Jehol Biota are two successive Lagerstätte assemblages that collectively offer a taphonomically consistent window into the Mesozoic life of northeast Asia over a significant span of geologic time.

Rugosodon eurasiaticus: An Oxfordian Jurassic Multituberculate, Early Example of the Wildly Successful Mammal Clade

The 160 million-year-old fossil of an extinct rodent-like creature from China is helping to explain how multituberculates—the most evolutionarily successful and long-lived mammalian lineage in the fossil record—achieved their dominance.

This fossil find—the oldest ancestor in the multituberculate family tree—represents a newly discovered species known as Rugosodon eurasiaticus. The nearly complete skeleton provides critical insights into the traits that helped such multituberculates thrive in their day. For example, the fossil reveals teeth that were adapted to gnawing plants and animals alike, as well as ankle joints that were highly adept at rotation.

In light of these findings, researchers suggest that R. eurasiaticus paved the way for later plant-eating and tree-dwelling mammals.

Chong-Xi Yuan from the Chinese Academy of Geological Sciences in Beijing, China, along with Chinese and American colleagues, report their analysis of the fossil in the 16 August issue of Science.

The multituberculates flourished during the Cretaceous era, which ended over 60 million years ago. Much like today's rodents, they filled an extremely wide variety of niches—below the ground, on the ground and in the trees—and this new fossil, which resembles a small rat or a chipmunk, possessed many of the adaptations that subsequent species came to rely upon, the researchers say.

"The later multituberculates of the Cretaceous [era] and the Paleocene [epoch] are extremely functionally diverse: Some could jump, some could burrow, others could climb trees and many more lived on the ground," explained Zhe-Xi Luo, a co-author of the Science report. "The tree-climbing multituberculates and the jumping multituberculates had the most interesting ankle bones, capable of 'hyper-back-rotation' of the hind feet."

"What is surprising about this discovery is that these ankle features were already present in Rugosodon—a land-dwelling mammal," he said. (Such highly mobile ankle joints are normally associated with the foot functions of animals that are exclusively tree-dwellers—those that navigate uneven surfaces.)

Additionally, R. eurasiaticus could eat many different types of food, according to the researchers. The fossil—particularly its dentition, which reveals teeth designed for shearing plant matter—confirms a 2012 analysis of tooth types that suggested multituberculates consumed an animal-dominated diet for much of their existence, later diversifying to a plant-dominated one.

Multituberculates arose in the Jurassic period and went extinct in the Oligocene epoch, occupying a diverse range of habitats for more than 100 million years before they were out-competed by more modern rodents. By the end of their run on the planet, multituberculates had evolved complex teeth that allowed them to enjoy vegetarian diets and unique locomotive skills that enabled them to traverse treetops. Both adaptations helped them to become dominant among their contemporaries.

Arboroharamiya: What a Single Fossil Can do to a Nice "Neat" Phylogeny

A new arboreal haramiyid shows the diversity of crown mammals in the Jurassic period

Authors:

1. Xiaoting Zheng (a,b)

2. Shundong Bi (c,d)

3. Xiaoli Wang (a,b_

4. Jin Meng (c,e)

Affiliations:

a. Institute of Geology and Paleontology, Linyi University, Shuangling Road, Linyi City, Shandong 276005, China

b. Shandong Tianyu Museum of Nature, Pingyi, Shandong 273300, China

c. Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China

d. Department of Biology, Indiana University of Pennsylvania, Indiana, Pennsylvania 15705, USA

e. Division of Paleontology, American Museum of Natural History, Central Park West and 79th Street, New York, New York 10024, USA

Abstract:

A major unsolved problem in mammalian evolution is the origin of Allotheria, including Multituberculata and Haramiyida. Multituberculates are the most diverse and best known Mesozoic era mammals and ecologically resemble rodents, but haramiyids are known mainly from isolated teeth, hampering our search for their phylogenetic relationships. Here we report a new haramiyid from the Jurassic period of China, which is, to our knowledge the largest reported so far. It has a novel dentition, a mandible resembling advanced multituberculates and postcranial features adapted for arboreal life. Our phylogenetic analysis places Haramiyida within crown Mammalia, suggesting the origin of crown Mammalia in the Late Triassic period and diversification in the Jurassic, which contrasts other estimated divergence times of crown Mammalia. The new haramiyid reveals additional mammalian features of the group, helps to identify other haramiyids represented by isolated teeth, and shows again that, regardless of various phylogenetic scenarios, a complex pattern of evolution involving many convergences and/or reversals existed in Mesozoic mammals.

It begs the question...given the other  Haramiyid which was also found, how good are teeth for classifying mammals? 

The Paleoecology of Oxfordian Jurassic Wyoming, USA

Palaeoecology of the marine reptiles of the Redwater Shale Member of the Sundance Formation (Jurassic) of central Wyoming, USA

Authors:

1. JUDY A. MASSARE (a)
2. WILLIAM R. WAHL (b)
3. MIKE ROSS (c)
4. MELISSA V. CONNELY (d)

Affiliations:

a. Earth Sciences Department, SUNY College at Brockport, Brockport, NY 14420, USA

b. Wyoming Dinosaur Center, Thermopolis, WY 82443, USA

c. 2614 Navarre Street, Casper, WY 82601, USA

d. Earth Science Department, Casper College, Casper, WY 82601, USA

Abstract:

The Redwater Shale Member (Oxfordian) of the Sundance Formation was deposited in the foreland basin of the Cordillera during the last and largest marine transgression of the Jurassic in North America. One ichthyosaur (Ophthalmosaurus natans), two cryptocleidoid plesiosaurs (Tatenectes laramiensis, Pantosaurus striatus) and one pliosauromorph (Megalneusaurus rex) are known from the Redwater Shale Member. Ichthyosaurs are much more abundant than plesiosaurs, making up almost 60% of the fauna. No actinopterygian fish have been found, although four species have been identified from the lower Sundance Formation. At least one hybodont shark and one neoselachian are known from rare isolated teeth. The main food source for the marine reptiles was belemnoids, as indicated by preserved gut contents for all four species. In comparison, the better known and slightly older Peterborough Member of the Oxford Clay Formation of England, has a much higher taxonomic and ecological diversity, especially in the plesiosaurs, marine crocodiles, and fish. The lower diversity in the Redwater Shale Member probably reflects a much lower primary productivity in the Sundance Sea, as well as restricted migration from the open ocean to the north.

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!

Juramaia sinensis: Earliest Known Eutherian Mammal?

A remarkably well-preserved fossil discovered in northeast China provides new information about the earliest ancestors of most of today's mammal species—the placental mammals. According to a paper published August 25 in the prestigious journal Nature, this fossil represents a new milestone in mammal evolution that was reached 35 million years earlier than previously thought, filling an important gap in the fossil record and helping to calibrate modern, DNA-based methods of dating the evolution.

The paper by a team of scientists led by Carnegie Museum of Natural History paleontologist Zhe-Xi Luo describes Juramaia sinensis, a small shrew-like mammal that lived in China 160 million years ago during the Jurassic period. Juramaia is the earliest known fossil of eutherians—the group that evolved to include all placental mammals, which provide nourishment to unborn young via a placenta. As the earliest known fossil ancestral to placental mammals, Juramaia provides fossil evidence of the date when eutherian mammals diverged from other mammals: metatherians (whose descendants include marsupials such as kangaroos) and monotremes (such as the platypus). As Luo explains, "Juramaia, from 160 million years ago, is either a great-grand-aunt, or a 'great-grandmother' of all placental mammals that are thriving today."

[...]

The fossil of Juramaia sinensis was discovered in the Liaoning Province in northeast China and examined in Beijing by Zhe-Xi Luo and his collaborators: Chong-Xi Yuan and Qiang Ji from the Chinese Academy of Geological Sciences, and Qing-Jin Meng from the Beijing Museum of Natural History, where the fossil is stored. The name Juramaia sinensis means "Jurassic mother from China." The fossil has an incomplete skull, part of the skeleton, and, remarkably, impressions of residual soft tissues such as hair. Most importantly, Juramaia's complete teeth and forepaw bones enable paleontologists to pin-point that it is closer to living placentals on the mammalian family tree than to the pouched marsupials, such as kangaroos.

less than no time...but could not resist.

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?

Darwinopterus: Glider Hunter

An international group of researchers from the University of Leicester (UK), and the Geological Institute, Beijing (China) have identified a new type of flying reptile – providing the first clear evidence of an unusual and controversial type of evolution.

Pterosaurs, flying reptiles, also known as pterodactyls, dominated the skies in the Mesozoic Era, the age of dinosaurs, 220-65 million years ago. Scientists have long recognized two different groups of pterosaurs: primitive long-tailed forms and their descendants, advanced short-tailed pterosaurs some of which reached gigantic size. These groups are separated by a large evolutionary gap, identified in Darwin's time, that looked as if it would never be filled – until now.

Details of a new pterosaur, published today in the Proceedings of the Royal Society B: Biological Sciences fits exactly in the middle of that gap. Christened Darwinopterus, meaning Darwin's wing, the name of the new pterosaur honours the 200th anniversary of Charles Darwin's birth and the 150th anniversary of the publication of On the origin of species.

Gaps in the fossil record are common – only a tiny proportion of all the animals and plants that ever lived were fortunate enough to become fossilised, and only a tiny proportion of these have been collected so far. Consequently, our understanding, both of the history of particular groups such as pterosaurs, and of the evolutionary processes that generated those histories, is still patchy and often controversial.

More than 20 fossil skeletons of Darwinopterus, some of them complete, were found earlier this year in north-east China in rocks dated at around 160 million years old. This is close to the boundary between the Middle and Late Jurassic and at least 10 million years older than the first bird, Archaeopteryx. The long jaws, rows of sharp-pointed teeth and rather flexible neck of this crow-sized pterosaur suggest that it might have been hawk-like, catching and killing other contemporary flying creatures. These included various pterosaurs, tiny gliding mammals and small, pigeon-sized, meat-eating dinosaurs that, aided by their feathered arms and legs had recently taken to the air, and would later evolve into birds.

"Darwinopterus came as quite a shock to us" explained David Unwin part of the research team and based at the University of Leicester's School of Museum Studies. "We had always expected a gap-filler with typically intermediate features such as a moderately elongate tail – neither long nor short – but the strange thing about Darwinopterus is that it has a head and neck just like that of advanced pterosaurs, while the rest of the skeleton, including a very long tail, is identical to that of primitive forms".

Dr Unwin added: "The geological age of Darwinopterus and bizarre combination of advanced and primitive features reveal a great deal about the evolution of advanced pterosaurs from their primitive ancestors. First, it was quick, with lots of big changes concentrated into a short period of time. Second, whole groups of features (termed modules by the researchers) that form important structures such as the skull, the neck, or the tail, seem to have evolved together. But, as Darwinopterus shows, not all these modules changed at the same time. The head and neck evolved first, followed later by the body, tail, wings and legs. It seems that natural selection was acting on and changing entire modules and not, as would normally be expected, just on single features such as the shape of the snout, or the form of a tooth. This supports the controversial idea of a relatively rapid "modular" form of evolution.

Paper anyone?