Saturday, February 18, 2017

Hatzegopteryx where top predators of Cretaceous Romania


A new study of neck biomechanics in Neck biomechanics indicate that giant Transylvanian azhdarchid pterosaurs were short-necked arch predators. 


Azhdarchid pterosaurs include the largest animals to ever take to the skies with some species exceeding 10 metres in wingspan and 220 kg in mass. Associated skeletons show that azhdarchids were long-necked, long-jawed predators that combined a wing planform suited for soaring with limb adaptations indicative of quadrupedal terrestrial foraging. The postcranial proportions of the group have been regarded as uniform overall, irrespective of their overall size, notwithstanding suggestions that minor variation may have been present.

Like all azhdarchid pterosaurs, Hatzegopteryx was probably a terrestrially foraging generalist predator. It is significantly larger than any other terrestrial predator from Maastrichtian Europe; due to its large size in an environment otherwise dominated by island dwarf dinosaurs, with no large hypercarnivorous theropods in the region, it has been suggested that Hatzegopteryx played the role of an apex predator in the Haţeg Island ecosystem. The robust anatomy of Hatzegopteryx suggests that it may have tackled larger prey than other azhdarchids, including animals too large to swallow whole; similarly, some modern storks (particularly the marabou stork and the jabiru) are known to attack and kill large prey such as flamingoes, and occasionally children, with their beaks. Meanwhile, other giant azhdarchids like Arambourgiania would probably have instead fed on small prey (up to the size of a human), including hatchling or small dinosaurs and eggs. Another pterosaur, Thalassodromeus, has similarly been suggested to be raptorial.

Credit: 
*https://peerj.com/articles/2908/
*en.wikipedia.com 
*image - Mark Witton 

Wednesday, September 28, 2016

Triassic Reptile Had ‘Third Eye’

ഒരു മുതലയുടെ അത്ര മാത്രം വലിപ്പം ഉണ്ടായിരുന്ന ഉരഗം ആണ് ട്രൈഒപ്റ്റിക്കസ് , പേര് സൂചിപ്പിക്കുന്ന പോലെ തന്നെ ഇവയുടെ തലയോട്ടിയിൽ കണ്ണ് കുഴിയോട് സാമ്യം ഉള്ള ഒരു ദ്വാരം പാലിയെന്റോളോജിസ്റ്റുകൾ കണ്ടെത്തി .

Paleontologists have described a completely unexpected new species of reptile that lived 230 million years ago (Triassic period).

The ancient reptile has been given the official name Triopticus primus, which means ‘the first of three eyes.’
“From the Latin ‘tri’ (three) and ‘optic’ (vision) for the large opening in the skull roof, resembling a third eye socket. The specific name is from the Latin ‘primus’ (first),” the paleontologists explained.

കൂടുതൽ വായനക്ക് 
http://www.cell.com/current-biology/abstract/S0960-9822(16)30860-0 

Sunday, September 25, 2016

Psittacosaurus Used Camouflage, New findings

3D Camouflage in an Ornithischian Dinosaur


Countershading was one of the first proposed mechanisms of camouflage . A dark dorsum and light ventrum counteract the gradient created by illumination from above, obliterating cues to 3D shape . Because the optimal countershading varies strongly with light environment , pigmentation patterns give clues to an animal’s habitat. Indeed, comparative evidence from ungulates shows that interspecific variation in countershading matches predictions: in open habitats, where direct overhead sunshine dominates, a sharp dark-light color transition high up the body is evident; in closed habitats (e.g., under forest canopy), diffuse illumination dominates and a smoother dorsoventral gradation is found. We can apply this approach to extinct animals in which the preservation of fossil melanin allows reconstruction of coloration . Here we present a study of an exceptionally well-preserved specimen of Psittacosaurus sp. from the Chinese Jehol biota . This Psittacosaurus was countershaded with a light underbelly and tail, whereas the chest was more pigmented. Other patterns resemble disruptive camouflage, whereas the chin and jugal bosses on the face appear dark. We projected the color patterns onto an anatomically accurate life-size model in order to assess their function experimentally. The patterns are compared to the predicted optimal countershading from the measured radiance patterns generated on an identical uniform gray model in direct versus diffuse illumination. These studies suggest that Psittacosaurus sp. inhabited a closed habitat such as a forest with a relatively dense canopy.
  • Preserved pigments in the dinosaur Psittacosaurus suggest countershading camouflage
  • We predicted the optimal countershading camouflage for different light environments
  • The dinosaur’s patterns would have been cryptic in a forest, but not open, habitat
  • We can also infer that dinosaur predators used shape-from-shading cues to detect prey


 Model of Psittacosaurus sp. based on skin and pigmentation patterns (specimen from the Senckenberg Museum, Germany). Image credit: Jakob Vinther et al.


Close examination of melanosomes preserved in the specimen of Psittacosaurus preserved with integument indicated that the animal was countershaded, likely due to preferring a habitat in dense forests with little light, much like many modern species of forest-dwelling deer and antelope; stripes and spots on the limbs may represent disruptive coloration. The specimen also had dense clusters of pigment on its shoulders, face (possibly for display), and cloaca (which may have had an antimicrobial function), as well as large patagia on its hind legs that connected to the base of the tail. Its large eyes indicate that it also likely had good vision, which would have been useful in finding food or avoiding predators. The authors were unable to determine which species of Jehol Formation Psittacosaurus the specimen belonged to due to the way the skull is preserved, but ruled out P. mongoliensis, based on hip features.

Credit: 
*cell.com  
*en.wikipedia.com 
* Jakob Vinther et al. 2016. 3D Camouflage in an Ornithischian Dinosaur. Current Biology 26: 1-7; doi: 10.1016/j.cub.2016.06.065

Tuesday, July 12, 2016

Spinosaurus aegyptiacus


Spinosaurus (meaning "spine lizard") is a genus of theropod dinosaur that lived in what now is North Africa, during the lower Albian to lower Cenomanian stages of the Cretaceous period, about 112 to 97 million years ago. This genus was known first from Egyptian remains discovered in 1912 and described by German paleontologist Ernst Stromer in 1915. The original remains were destroyed in World War II, but additional material has come to light in recent years. It is unclear whether one or two species are represented in the fossils reported in the scientific literature. The best known species is S. aegyptiacus from Egypt, although a potential second species, S. maroccanus, has been recovered from Morocco.


Spinosaurus was among the largest of all known carnivorous dinosaurs, possibly larger than Tyrannosaurus and Giganotosaurus. Estimates published in 2005, 2007, and 2008 suggested that it was between 12.6–18 metres (41–59 ft) in length and 7 to 20.9 tonnes (7.7 to 23.0 short tons) in weight.[1][2][3] A new estimate published in 2014 and based on a more complete specimen, supported the earlier research, finding that Spinosaurus could reach lengths greater than 15 m (49 ft).[4] The skull of Spinosaurus was long and narrow, similar to that of a modern crocodilian. Spinosaurus is known to have eaten fish, and most scientists believe that it hunted both terrestrial and aquatic prey; evidence suggests that it lived both on land and in water as a modern crocodilian does. The distinctive spines of Spinosaurus, which were long extensions of the vertebrae, grew to at least 1.65 meters (5.4 ft) long and were likely to have had skin connecting them, forming a sail-like structure, although some authors have suggested that the spines were covered in fat and formed a hump. Multiple functions have been put forward for this structure, including thermoregulation and display.

content credit en.wikipedia.
image credit : Durbed @commons.wikimedia

Wednesday, December 16, 2015

Kunbarrasaurus ieversi


Kunbarrasaurus ieversi: New ankylosaurs Dinosaur Species Discovered.
The near-complete skeleton of the 100 million-year-old (Cretaceous period) beast, including most of the skull and mandible, along with postcranial material, was discovered in 1989 in the Allaru Mudstone on Marathon Station near Richmond, north-western Queensland, by Mr Ian Ievers.

Minmi is the only known genus of ankylosaurian dinosaur from Australia. Seven specimens are known, all from the Lower Cretaceous of Queensland. Only two of these have been described in any detail: the holotype specimen Minmi paravertebra from the Bungil Formation near Roma, and a near complete skeleton from the Allaru Mudstone on Marathon Station near Richmond, preliminarily referred to a possible new species of Minmi. The Marathon specimen represents one of the world’s most complete ankylosaurian skeletons and the best-preserved dinosaurian fossil from eastern Gondwana. Moreover, among ankylosaurians, its skull is one of only a few in which the majority of sutures have not been obliterated by dermal ossifications or surface remodelling. Recent preparation of the Marathon specimen has revealed new details of the palate and narial regions, permitting a comprehensive description and thus providing new insights cranial osteology of a basal ankylosaurian. The skull has also undergone computed tomography, digital segmentation and 3D computer visualisation enabling the reconstruction of its nasal cavity and endocranium. The airways of the Marathon specimen are more complicated than non-ankylosaurian dinosaurs but less so than derived ankylosaurians. The cranial (brain) endocast is superficially similar to those of other ankylosaurians but is strongly divergent in many important respects. The inner ear is extremely large and unlike that of any dinosaur yet known. Based on a high number of diagnostic differences between the skull of the Marathon specimen and other ankylosaurians, we consider it prudent to assign this specimen to a new genus and species of ankylosaurian. Kunbarrasaurus ieversi gen. et sp. nov. represents the second genus of ankylosaurian from Australia and is characterised by an unusual melange of both primitive and derived characters, shedding new light on the evolution of the ankylosaurian skull.

REF :Leahey L.G. et al. 2015. Cranial osteology of the ankylosaurian dinosaur formerly known as Minmi sp. (Ornithischia: Thyreophora) from the Lower Cretaceous Allaru Mudstone of Richmond, Queensland, Australia. PeerJ 3: e1475; doi: 10.7717/peerj.1475

mage credit: © Australian Geographic. 

Tuesday, October 6, 2015

ദിനോസറുകളുടെ വംശനാശം



തുടക്ക ജുറാസ്സിക് കാലം തൊട്ടു് അന്ത്യ ക്രിറ്റേഷ്യസ് വരെ ഭൂമിയിൽ ഏറ്റവും പ്രാതിനിധ്യമുള്ള ജീവിയും ദിനോസറുകളായിരുന്നു. എന്നാൽ, അന്ത്യ ക്രിറ്റേഷ്യസ് കാലത്ത് സംഭവിച്ച, ഭൂമിയുടെ ചരിത്രം കണ്ട ഒരു വലിയ വംശനാശത്തിൽ (കേ-ടി വംശനാശം) അന്ന് ജീവിച്ചിരുന്ന മിക്ക ദിനോസർ വർഗ്ഗങ്ങളും നശിച്ചു. ഉൽക്ക പതിച്ചതു കൊണ്ട് മാത്രം അല്ല പരിണിത ഫലമായി ഇന്ത്യയിലെ ഡെക്കാനിൽ ഉണ്ടായ അഗ്നിപർവതസ്ഫോടനങ്ങളുടെ കൂടെ ഫലമാണ് ഡൈനസോറുകളുടെ നാശത്തിനു കാരണമായ കേ-ടി വംശനാശം എന്ന് പുതിയ പഠന റിപ്പോർട്ടുക്കൾ സൂചിപ്പിക്കുന്നു.

ഇവ നാമാവശേഷമായതിനെക്കുറിച്ചു പല സിദ്ധാന്തങ്ങളും നിലവിലുണ്ട്‌ - ഉൽക്കകൾ പതിച്ചതുകൊണ്ടോ അഗ്നിപർവതസ്ഫോടനത്താലോ ഭൂമിയിലുണ്ടായ മാറ്റങ്ങളാണു ഡൈനസോറുകളുടെ നാശത്തിനു കാരണമെന്നാണു കരുതപ്പെടുന്നത്.



ക്രിറ്റേഷ്യസ്‌ കാലഘട്ടം
 ഭുമിയുടെ ചരിത്രം കണ്ട ഒരു വലിയ വംശനാശമാണ് ക്രിറ്റേഷ്യസ്‌ കാലഘട്ടം സാക്ഷ്യം വഹിച്ചത്. ഇതിനെ കേ - ടി വംശനാശം എന്ന് വിളിക്കുന്നു. ഇത് കേവലം ദിനോസറുകളെ മാത്രം അല്ല ബാധിച്ചത്, ഈ കാലയളവിൽ ജീവിച്ചിരുന്ന എഴുപത്തഞ്ച്  ശതമാനം ജീവികളും ഈ വംശനാശത്തിൽ നശിച്ചുപോയി ഇതിൽ കരയിൽ ഉണ്ടായിരുന്ന പറക്കാത്ത ഇനത്തിൽ പെട്ട എല്ലാ ദിനോസറുകളും , കടലിൽ വസിച്ചിരുന്ന വലിയ ഉരഗങ്ങൾ , പറക്കുന്ന ഉരഗങ്ങൾ എന്നിവയെല്ലാം പെടും.എന്നാൽ ഈ വംശനാശം പെട്ടന്ന് ഉള്ള ഒന്നായിരുന്നില്ല മറിച്ച് ആയിരകണക്കിന് വർഷങ്ങൾ കൊണ്ടാണ് ഇത് സംഭവിച്ചത് .

An international team of scientists from India and the United States has uncovered evidencein 2015 that a massive comet or asteroid impact on Earth 66 million years ago accelerated the eruptions of volcanoes in what is now the Deccan Traps of India for thousands of years, and that together these two catastrophes wiped out the dinosaurs and many other groups of organisms.

The new measurements of Deccan volcanic activity indicate a dramatic increase in the rate of eruption of the volcanoes within 50,000 years of the Chicxulub impact.

Collide impact and flood volcanism compete as leading candidates for the cause of terminal-Cretaceous mass extinctions. High-precision 40Ar/39Ar data indicate that these two mechanisms may be genetically related, and neither can be considered in isolation. The existing Deccan Traps magmatic system underwent a state shift approximately coincident with the Chicxulub impact and the terminal-Cretaceous mass extinctions, after which ~70% of the Traps' total volume was extruded in more massive and more episodic eruptions. Initiation of this new regime occurred within ~50,000 years of the impact, which is consistent with transient effects of impact-induced seismic energy. Post-extinction recovery of marine ecosystems was probably suppressed until after the accelerated volcanism waned.  


Massive eruptions formed the Deccan Traps flood basalts in India at around the same time as the mass extinction event 65 million years ago. Renne et al. precisely dated the massive volcanic field, which suggests a simultaneous increase in volcanism associated with the famous Chicxulub impact. Strong ecologic recovery may have been impossible until the volcanism slowed down 500,000 years later.

Saturday, August 1, 2015

ജുറാസിക് കാലഘട്ടത്തിലെ ഈന്ത് ചെടികള്‍ ഇന്ത്യയിൽ കണ്ടെത്തി

ജുറാസിക് കാലഘട്ടത്തില്‍ ഭൂമിയിലുണ്ടായിരുന്ന ഈന്ത് വര്‍ഗത്തില്‍പ്പെട്ട രണ്ട് ചെടികളെ ഗവേഷകര്‍ ഒഡിഷയില്‍ കണ്ടെത്തി. ജീവിക്കുന്ന ഫോസില്‍ എന്നാണ് സൈക്കാസ് (ഈന്ത്) കുടുംബത്തിലെ ചെടികള്‍ വിശേഷിപ്പിക്കപ്പെടുന്നത്.

സൈക്കാസ് ഒറിക്‌സന്‍സിസ്, സൈക്കാസ് നയാഗാര്‍ഹന്‍സിസ് എന്നിങ്ങനെയാണ് കണ്ടെത്തിയ ചെടികളുടെ ശാസ്ത്രീയനാമം. 

ഭൂമിയില്‍ 20 കോടി വര്‍ഷങ്ങള്‍ക്ക് മുമ്പാണ് ദിനോസറുകള്‍ അടക്കിവാണ ജുറാസിക് കാലഘട്ടം നിലനിന്നിരുന്നത്. നീണ്ട ഇലകളുള്ള സൈക്കാസ് വിഭാഗത്തിലെ ചെടികള്‍ ഈ കാലഘട്ടത്തില്‍ സുലഭമായിരുന്നു. ജുറാസിക് യുഗത്തില്‍ നിലനിന്നിരുന്ന ചുരുക്കം സസ്യവര്‍ഗങ്ങളാണ് ഇന്ന് ഭൂമിയില്‍ അവശേഷിക്കുന്നത്.  

Indian scientists  have discovered two new Cycads species of plants in Odisha which were dominant some 201 million to 145 million years ago, popularly known as the Jurassic period. 

Cycads are considered to be an ancient group of seed plants which have crown of large compound leaves and a stout trunk. They are regarded as living fossils.
Cycas is the type genus and the only genus recognised in the family Cycadaceae.

The discovery of the two new species was published in July issue of Asian Journal of Conservation Biology.
IANS