Rubecula wrote: »
I was just wondering if the dinos such as the spiny ones above ever developed toxins ?
I think that if they did the defence would be formidable/
Adam Khor wrote: »
I have wondered the same! The spines themselves don´t have (as far as I know) grooves that would indicate a venom inoculation system, but then neither does the barb of a stingray- instead their barb is "coated" on a poisonous mucus produced by special cells in their epidermis (no actual poison glands involved).
So maybe we shouldn´t discard the idea...
The spiniest sauropods, such as Amargasaurus and Bajadasaurus, were relatively small as sauropods go, so it would make sense for them to have some sort of extra defense against the large predators they likely coexisted with.
The research helps answer a long-standing mystery, says study author Kayleigh Wiersma, a paleontologist at the University of Bonn in Germany. Since the 1930s, long rows of isolated sauropod teeth—still perfectly arranged in the position they would have been in the mouth during life—have been found embedded as fossils in rocks, but with not a scrap of fossil bone encasing them. “There must have been something holding them in place,” she says. “Otherwise they would have been scattered all around the dig site.”
Now, they have studied seven sets of isolated tooth rows from a variety of sauropod species, including German “dwarf” sauropod Europasaurus, as well the groups that include well-known species such as Diplodocus, Brachiosaurus, and Apatosaurus.
The scientists report the likely presence of beaks in many of these species. The finding is based on seven fossils of isolated rows of up to 40 teeth, as well as a detailed analysis of the skulls and teeth of Camarasaurus and Europasaurus. The teeth fossils in these species typically show surface wear only about 50% of the way down to the jaw, Wiersma says. That indicates the teeth were once deeply embedded in a “rhamphotheca,” or beaklike structure made of keratin (which also forms our hair and nails, as well as bird beaks and feathers). Existing reconstructions of sauropod faces would have left the tooth roots exposed and the teeth too loosely attached to the skull, the authors say. In Camarasaurus and Europasaurus the pair also found tiny pits in the surface bone of the jaw, which may indicate the presence of blood vessels that once nourished beak tissue.
Despite its iconic status, in dinosaur books and movies like Jurassic Park, Brachiosaurus is actually a pretty rare sauropod(..) Camarasaurus is known from over 200 individuals, Apatosaurus and Diplodocus from over 100 individuals apiece, but Brachiosaurus is only known from about 10. So any new specimens are important.
A rib bone fossil from about 100 million years ago is believed to be from the second largest dinosaur to have roamed Japan, researchers said.
The fossil, from a herbivore, was excavated from a stratum on Goshourajima island in the city, according to an announcement on Feb. 27 by two museums that jointly conducted the research.
The fossilized piece of the rib bone is 42 centimeters long, 18 cm wide and 9 cm thick. A reconstruction of the entire bone measures 1.4 meters long.
The researchers estimated the overall length of the dinosaur at about 15 meters, making it the largest ever found in Kyushu.
Dinosaur locomotion and biomechanics, especially of their pelvic girdles and hindlimbs, have been analyzed in numerous studies.
However, detailed volumetric musculoskeletal models of their tails are rarely developed. Here, we present the first detailed three-dimensional volumetric reconstruction of the caudal epaxial and hypaxial musculature of the Late Jurassic sauropod Giraffatitan brancai, and highlight the importance and necessity of 3D modeling in musculoskeletal reconstructions.
The tail of this basal macronarian is relatively short compared to diplodocids and other coexisting macronarians.
The center of mass lies well in front of the hindlimbs, which support only ca. half the body weight. Still, our reconstruction suggests a total weight for the entire tail of ca. 2500 kg.
We conclude that the hypaxial and tail-related hindlimb muscles (most specifically the M. caudofemoralis longus and its counterpart the M. ilioischiocaudalis) in Giraffatitan were well developed and robustly built, compensating for the shorter length of the M. caufodemoralis longus, the main hindlimb retractor muscle, in comparison with other sauropods. Our methodology allows a better-constrained reconstruction of muscle volumes and masses in extinct taxa, and thus force and weight distributions throughout the tail, than non-volumetric approaches.