There was no "‘Northern Branch of Neotethys” During the Jurassic

Where are the remnants of a Jurassic ocean in the eastern Mediterranean region?

Authors:

Eyuboglu et al

Abstract:

The subduction polarity of Tethyan oceanic lithosphere during Jurassic is a controversial topic in relation to the geodynamic evolution of the Alpine–Himalayan system. We present new geological, geochemical and zircon U–Pb data from four different regions of the Eastern Pontides Orogenic Belt, a key area of the Alpine–Himalayan system. We discuss the origin of the magmatism and also the existence of an ocean in the eastern Mediterranean region during the Jurassic period. Jurassic intrusions, predominantly gabbro, tonalite and minor diorite, are well exposed in the southern and axial zones of the orogenic belt. Thermobarometry indicates that high-pressure (6–10 kb) crystallization of these intrusions occurred at temperatures of 1183–1250 °C. Zircon U–Pb dating from 10 samples show ages between 195 and 165 Ma, indicating that magmatism occurred between Sinemurian and Callovian time. We characterize the intrusions from electron microprobe, zircon geochronology, and whole rock and Sr, Nd, and Pb isotopes. Our data show that the studied intrusions are broadly tholeiitic, except for two calc-alkaline bodies, and formed in an arc-related setting with minimal involvement of older crust or sediment.

The most widely accepted model proposes that the ultramafic–mafic rocks exposed between the Pontide arc and the Tauride belt are remnants of a Jurassic Penrose-type and/or suprasubduction zone ophiolite. However, new zircon U–Pb age data from mafic lithologies cutting the Kop ultramafic massif do not support this model and clearly indicate that the ultramafic lithologies are Paleozoic or older in age and are not remnants of a Jurassic ocean that known as ‘’Northern Branch of Neotehtys”.

Ichthyosaurus anningae: a new Fish Lizard From Hettangian/Sinemurian–Pliensbachian Jurassic England

A new species of Ichthyosaurus from the Lower Jurassic of West Dorset, England, U.K.

Authors:

Lomax et al

Abstract:

We describe a new species of Lower Jurassic (Hettangian/Sinemurian–Pliensbachian) ichthyosaur, Ichthyosaurus anningae, sp. nov., from west Dorset, England, U.K. The holotype of I. anningae (DONMG:1983.98), at least a subadult, is from the lower Pliensbachian Stonebarrow Marl Member (Charmouth Mudstone Formation). It is the most complete ichthyosaur known from this time interval worldwide. The species is assigned to Ichthyosaurus on the basis of humerus, forefin, and pectoral girdle morphologies. Diagnostic features of the species include a short, robust humerus with prominent processes; a femur in which the proximal width is almost as large as the distal width; and a very small femur relative to the humerus (humerus/femur ratio >1.7). Four other specimens, at least three of which are juveniles, are referred to this species. The new species may display sexual dimorphism in humeral morphology, but this cannot be confirmed due to a lack of stratigraphic information. With the recognition of I. anningae, at least three and possibly as many as five ichthyosaur species, representing three genera, are known from the Pliensbachian.

Evidence of a Significant Biological/Enviromental Event During the Upper Sinemurian Jurassic

Isotopic and palynological evidence for a new Early Jurassic environmental perturbation

Authors:

Riding et al

Abstract:

The Early Jurassic Epoch was a predominantly greenhouse phase of Earth history, but a comprehensive understanding of its climate dynamics is hampered by a lack of high resolution multi-proxy environmental records. Here we report a geologically brief (approximately several hundred thousand years) negative carbon isotope excursion (CIE) of 2–3‰ in both marine and terrestrial materials, recognised for the first time for the Late Sinemurian Substage (Early Jurassic, ~ 194 Ma) of eastern England. The Late Sinemurian carbon isotope excursion, which is termed the S-CIE herein, is accompanied by peaks in the abundance of the pollen grain Classopollis classoides and the dinoflagellate cyst Liasidium variabile. Classopollis classoides was thermophilic and is a reliable proxy for hot/warm climatic conditions. Liasidium variabile is interpreted as thermophilic and eutrophic using multivariate statistics, its fluorescence properties being similar to living heterotrophic dinoflagellate cysts, and its association with C. classoides. Moreover, the morphological and ecological similarities of L. variabile to the Cenozoic genus Apectodinium are noteworthy. The co-occurrence of the acmes of C. classoides and L. variabile with a negative CIE is interpreted here as having wide geographical significance due to the marine and terrestrial carbon isotope signals being precisely in phase within an open marine setting. This is consistent with an oceanic–atmospheric injection of isotopically-light carbon, coupled with global warming and increased marginal marine nutrient supply, possibly the result of increased precipitation due to an enhanced hydrological cycle or a seasonally-stratified water column. A probable sea level rise of at least regional extent has been identified at the L. variabile event in other records, which supports this putative phase of global warming. All these features are common to the Paleocene/Eocene thermal maximum (PETM, ~ 56 Ma), and there are also similarities with the Early Toarcian oceanic anoxic event (T-OAE, ~ 182 Ma).

Storms Periodically Reoxygenated the Lusitanian Basin During the Sinemurian Jurassic

Spatial characterization of the late Sinemurian (Early Jurassic) palaeoenvironments in the Lusitanian Basin

Authors:

Boussaha et al

Abstract:

The upper Sinemurian of the Lusitanian Basin (Portugal) is characterized by the deposition of carbonates (dolomitic limestones, limestones), sometimes enriched in organic matter (total organic carbon up to 22%). The main goal of this study is to understand the distribution of carbonates and organic matter-rich sediments in space and time, and to characterize the context of their deposition at the basin scale. Three sections located along a proximal–distal transect in the Lusitanian Basin and dated from the oxynotum to raricostatum ammonite zones (upper Sinemurian) have been studied for their microfacies and sedimentary structures, and correlated by means of ammonite and calcareous nannofossil biostratigraphy, and sequence stratigraphy. The proximal part of the basin is dominated by carbonates whereas organic-rich sediments and marl-limestone alternations are common in the distal part. Microfacies analysis shows a trend from high- to low-energy environments, which reflects a deepening trend in most of the basin within the raricostatum ammonite Zone. A forced regression took place in the earliest Pliensbachian, which is likely related to tectono-eustasy. This particular surface can be correlated at the regional level, to several basins of the western Tethys.

The presence of black shales in the distal part of the basin and of framboidal pyrite in the proximal part is interpreted as resulting from an episode of pervasive dysoxia/anoxia at the basin scale during this time interval. The basin recorded conditions varying from dysoxic/anoxic phases in times of water column stratification, to full oxygenation in times of intense mixing by storms, attested by the presence of storm-related sedimentary structures in some carbonate-rich deposits. The occurrence of upper Sinemurian sediments rich in organic matter in other basins, in England and Spain, in the same time interval (upper Sinemurian, raricostatum ammonite Zone) suggests that palaeoclimatic and palaeogeographic conditions were prone to the development of a supraregional dysoxia/anoxia.

How Dark is Your Santonian Cretaceous Mosasaur? Your Sinemurian Jurassic Ichthyosaur?

Unique finds of original pigment in fossilised skin from three multi-million-year old marine reptiles attract considerable attention from the scientific community. The pigment reveals that these animals were, at least partially, dark-coloured in life, which is likely to have contributed to more efficient thermoregulation, as well as providing means for camouflage and UV protection. Researchers at Lund University are among the scientists that made the spectacular discovery.

During the Age of the dinosaurs, huge reptiles, such as mosasaurs and ichthyosaurs, ruled the seas. Previously, scientists could only guess what colours these spectacular animals had; however, pigment preserved in fossilised skin has now been analysed at SP Technical Research Institute of Sweden and MAX IV Laboratory, Lund University, Sweden. The unique soft tissue remains were obtained from a 55 million-year-old leatherback turtle, an 85 million-year-old mosasaur and a 196 million-year-old ichthyosaur. This is the first time that the colour scheme of any extinct marine animal has been revealed.

"This is fantastic! When I started studying at Lund University in 1993, the film Jurassic Park had just been released, and that was one of the main reasons why I got interested in biology and palaeontology. Then, 20 years ago, it was unthinkable that we would ever find biological remains from animals that have been extinct for many millions of years, but now we are there and I am proud to be a part of it", said Johan Lindgren about the discovery of the ancient pigment molecules.

link.

New Sinemurian Jurassic Fossil From China Confirms Tritylodontids as Mammaliaforms

Pelvic morphology of a tritylodontid (Synapsida: Eucynodontia) from the Lower Jurassic of China, and some functional and phylogenetic implications

Authors:

1. Corwin Sullivan (a)
2. Jun Liu (a)
3. Eric M. Roberts (b)
4. Timothy D. Huang (c)
5. Chuanwei Yang (d)
6. Shiming Zhong (e)

Affiliations:

a. Key Laboratory of Vertebrate Evolution and Human Origins of the Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, 142, Xizhimenwai Dajie, 100044 Beijing, China

b. School of Earth and Environmental Sciences, James Cook University, Queensland, Australia

c. National Chung Hsing University, Taichung, Taiwan

d. Lufeng County Dinosaur Museum, Lufeng, Yunnan, China

e. Chuxiong Prefectural Museum, Chuxiong, Yunnan, China

Abstract:

Tritylodontids are specialised, herbivorous cynodonts whose exact phylogenetic position is controversial, with some authors regarding them as close relatives of mammaliaforms and others as members of the eucynodont clade Traversodontidae. The tritylodontid pelvis has been claimed to resemble that of mammaliaforms in having a narrow, rod-like ilium, but such claims have been strongly challenged because of the incompleteness of previously available tritylodontid pelvic material. However, a partial tritylodontid skeleton from the Lower Jurassic of China preserves nearly complete examples of all three pelvic elements in addition to both femora, providing unprecedented insight into the structure of the tritylodontid pelvis and the configuration of the hip joint. This specimen confirms that the iliac blade is rod-like, adding to the evidence for a close relationship between tritylodontids and mammaliaforms. Furthermore, femoral retraction appears to have been driven partly by gluteus musculature in tritylodontids, as in mammaliaforms.

Evidence of Eusocial Insects from the Hettangian/Sinemurian Jurassic of China?

Novel insect traces on a dinosaur skeleton from the Lower Jurassic Lufeng Formation of China

Authors:

1. Lida Xing (a, b)
2. Eric M. Roberts (c)
3. Jerald D. Harris (d)
4. Murray K. Gingras (e)
5. Hao Ran (f)
6. Jianping Zhang (a)
7. Xing Xu (g)
8. Michael E. Burns(b)
9. Zhiming Dong (g)

Affiliations:

a. School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China

b. Department of Biological Sciences, University of Alberta, 11455 Saskatchewan Drive, Edmonton, Alberta T6G 2E9, Canada

c. School of Earth and Environmental Science, James Cook University, Townsville, Qld 4811, Australia

d. Physical Sciences Department, Dixie State College, 225 South 700 East, St. George, Utah 84770, USA

e. Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada

f. Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection (Guangxi Normal University), Ministry of Education, Guilin 541004, China

g. Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China

Abstract:

Dense networks of burrow-like traces on the surfaces of bones are preserved on a partial skeleton of a prosauropod dinosaur (cf. Yunnanosaurus) from the Lower Jurassic Lufeng Formation in Yunnan, China. The traces, which gently meander across and, in places, shallowly excavate the surfaces of several axial and appendicular skeletal elements (total cumulative length over 29 m) consist of simple burrows, Y-shaped branches, overlapping intersections, and chambers. This unusual network is morphologically most similar to foraging traces of eusocial insects, particularly termites. Comparisons of known continental ichnofossils, demonstrate the novelty of this trace, which thus pertains to a new ichnotaxon, Taotieichnus orientalis ichnogen. et ichnosp. nov. Taotieichnus orientalis most closely resembles subaerial foraging galleries constructed of mud or carton (saliva and faecal material mixed with soil or partially digested wood particles) and produced by a range of subterranean termites. Periodic, possibly seasonal, use of carrion as a nutrient source, and the construction of carton foraging galleries over decomposing vertebrate carcasses, is a known, but little documented, dietary supplement for some xylophagus, neotropical termite species. These Early Jurassic traces constitute the earliest evidence of eusocial insect foraging behavior, and suggest that a possible adaptive radiation of stem- or crown-group termites as foragers—or, at least, opportunistic decomposers—of animal carcasses had already occurred by the Early Jurassic.

Lufengosaurus Embryonic Bonebed Found From Sinemurian Jurassic China

The great age of the embryos is unusual because almost all known dinosaur embryos are from the Cretaceous Period. The Cretaceous ended some 125 million years after the bones at the Lufeng site were buried and fossilized.

Led by University of Toronto Mississauga paleontologist Robert Reisz, an international team of scientists from Canada, Taiwan, the People's Republic of China, Australia, and Germany excavated and analyzed over 200 bones from individuals at different stages of embryonic development.

"We are opening a new window into the lives of dinosaurs," says Reisz. "This is the first time we've been able to track the growth of embryonic dinosaurs as they developed. Our findings will have a major impact on our understanding of the biology of these animals."

The bones represent about 20 embryonic individuals of the long-necked sauropodomorph Lufengosaurus, the most common dinosaur in the region during the Early Jurassic period. An adult Lufengosaurus was approximately eight metres long.

The disarticulated bones probably came from several nests containing dinosaurs at various embryonic stages, giving Reisz's team the rare opportunity to study ongoing growth patterns. Dinosaur embryos are more commonly found in single nests or partial nests, which offer only a snapshot of one developmental stage.

To investigate the dinosaurs' development, the team concentrated on the largest embryonic bone, the femur. This bone showed a consistently rapid growth rate, doubling in length from 12 to 24 mm as the dinosaurs grew inside their eggs. Reisz says this very fast growth may indicate that sauropodomorphs like Lufengosaurus had a short incubation period.

Paper link.

Jurassic Mammal Tracks Found at Dinosaur National Monument

Hundreds of tiny footprints left by mammals some 190 million years ago have been found on a canyon wall in a remote part of Dinosaur National Monument, park officials said Thursday.

The tracks are a rare find, mostly because they were left at a time when the area was a hostile, vast Sahara-like desert where towering sand dunes seldom preserved signs of animal life.

“It’s just astonishing,” Dan Chure, a paleontologist at the monument, said Thursday. “We were giggling like kids.”

He and paleontologist George Engelmann of the University of Nebraska at Omaha spotted the tracks July 8 while scouring the area for fossils and other evidence from the early Jurassic period. Dinosaur National Monument, founded because of its rich and plentiful supply of dinosaur bones, straddles the Utah-Colorado border.

Most of the tracks are the size of a dime or smaller. A few include impressions of up to four toes. The mammals — perhaps the size of a rat — were among the few species that were able to survive between large sand dune fields where there was water, dinosaurs and a few plants, Chure said.

Because they were living in a forbidding desert environment, most animals probably came out at night, including the small mammals who left the tracks, Chure said. He said it’s reasonable to assume the tracks were preserved by a layer of moisture that created a slight crust on the dune and kept the prints from blowing away.

whoa. kewl!