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Oldest known dinosaur nesting site discovered in South Africa
A fantastic discovery has been made in early Jurassic strata at the Golden Gate Highlands National Park, South Africa. The area has previously revealed many excellent fossils, including skeletons of prosauropod (early dinosaurs preceding Sauropods, and often bipedal) Massospondylus. In 1976, a block of siltstone was found to contain a partial egg clutch of this species with in ovo embryonic remains. A study led by Prof. Robert Reisz (University of Toronto), began in 2006 to investigate the site further and has uncovered a nesting site with several complete nests and fascinating evidence of complex reproductive behaviours. The nesting site is approximately 190 million years old, making it the oldest vertebrate nesting site of its kind, and 100 million years older than the previously oldest known nesting site with in ovo embryonic fossils. Read the rest of this entry
Possible discovery of venom in the lineage that led to modern birds
Researchers have discovered clues in a fossilized feathered dinosaur that suggests it may have used a venom delivery system.
Sinornithosaurus (closely related to Velociraptor and Microraptor) lived in the lower Cretaceous Period approximately 128 million years ago and the first fossils were discovered at the famous Yixian Formation in 1999. It was the fifth non-avian dinosaur genera discovered to sport feathers, and Sinornithosaurus serves as key evidence for the theory that modern birds evolved from dinosaurs by providing an explanation to counter the temporal paradox argument.
In 2009, Enpu Gong and fellow researchers discovered new characteristics when studying a fossilized Sinornithosaurus skull and their findings were published by PNAS. Here is the abstract:
Gong, E., L.D. Martin, D.E. Burnham, and A.R. Falk. (2009). “The birdlike raptor Sinornithosaurus was venomous.” Proceedings of the National Academy of Sciences, published online before print December 22, 2009, doi: 10.1073/pnas.0912360107
We suggest that some of the most avian dromaeosaurs, such as Sinornithosaurus, were venomous, and propose an ecological model for that taxon based on its unusual dentition and other cranial features including grooved teeth, a possible pocket for venom glands, and a groove leading from that pocket to the exposed bases of the teeth. These features are all analogous to the venomous morphology of lizards. Sinornithosaurus and related dromaeosaurs probably fed on the abundant birds of the Jehol forests during the Early Cretaceous in northeastern China.
Sinornithosaurus is believed by the research team to be the first venomous dinosaur to be discovered. Examination of the skull revealed many interesting features including very long maxillary teeth with grooves on the rear. This feature is seen in modern venomous reptiles but hasn’t been found in any non-venomous animals. Gong et al also discovered grooves between the base of the teeth and a cavity just above the teeth. They propose that this cavity is where the venom-gland would be located. Similar features are all found in modern venomous reptiles. The evidence seems to indicate a low-pressure delivery system similar to that used by the venomous lizard Heloderma horridum.
The team have also suggested that the very long teeth may be evidence that Sinornithosaurus preyed on small birds, as modern venomous snakes have long teeth in order to penetrate through the thick layers of feathers and still inject the venom.
Already famous for its feathers, and for becoming a key in solving the temporal paradox, this genera seems to have revealed yet another fascinating scientific discovery. Gong et al are now focusing their attention on the closely-related Microraptor to see if they can find evidence of a similar venom delivery system.
Peter Harrison
