Stegosauria

Showing results in 'Publications'. Show all posts
Mateus, O., Milàn J., Romano M., & Whyte M. A. (2011).  New finds of stegosaur tracks from the Upper Jurassic Lourinhã Formation, Portugal. Acta Palaeontologica Polonica. 56(1), 651-658. Abstractmateus_et_al_2011_-_deltapodus_with_skin_impressions_from_portugal.pdf

Eleven new tracks from the Upper Jurassic of Portugal are described and attributed to the stegosaurian ichnogenus Deltapodus. One track exhibits exceptionally well−preserved impressions of skin on the plantar surface, showing the stegosaur foot to be covered by closely spaced skin tubercles of ca. 6 mm in size. The Deltapodus specimens from the Aalenian of England represent the oldest occurrence of stegosaurs and imply an earlier cladogenesis than is recognized in the body fossil record.

Mateus, O., Maidment S., & Christiansen N. (2009).  A new long-necked 'sauropod-mimic' stegosaur and the evolution of the plated dinosaurs. Proceedings of the Royal Society of London B. 276, 1815-1821., Jan Abstractmateus_et_al_2009_stegosaur_miragaia_complete_with_suppl.pdfWebsite

Stegosaurian dinosaurs have a quadrupedal stance, short forelimbs, short necks, and are generally considered to be low browsers. A new stegosaur, Miragaia longicollum gen. et sp. nov., from the Late Jurassic of Portugal, has a neck comprising at least 17 cervical vertebrae. This is eight additional cervical vertebrae when compared with the ancestral condition seen in basal ornithischians such as Scutellosaurus.
Miragaia has a higher cervical count than most of the iconically long-necked sauropod dinosaurs. Long neck length has been achieved by ‘cervicalization’ of anterior dorsal vertebrae and probable lengthening of centra. All these anatomical features are evolutionarily convergent with those exhibited in the necks of
sauropod dinosaurs. Miragaia longicollum is based upon a partial articulated skeleton, and includes the only known cranial remains from any European stegosaur. A well-resolved phylogeny supports a new clade that unites Miragaia and Dacentrurus as the sister group to Stegosaurus; this new topology challenges the common view of Dacentrurus as a basal stegosaur.

Araújo, R., Mateus O., Walen A., & Christiansen N. (2009).  Preparation techniques applied to a stegosaurian Dinosaur from Portugal. Journal of Paleontological Techniques. 5, 1-24., Jan Abstractarajomateusetal2009.preparationtechn.pdfWebsite

General vertebrate paleontological techniques that have been used in the Museum of Lourinhã (Portugal) are presented here, in particular those applied to a stegosaurian dinosaur skeleton, Miragaia longicollum. A monolith jacket technique using polyurethane foam and plaster is presented. Mechanical preparation
techniques combining the use of an electric grinder and airscribes proved effective during the initial phases of preparation on well-preserved bone embedded in hard matrix. We also present a technique to mould monoliths in the early stages of preparation, creating a thin silicone rubber mould in several contiguous
parts. To mould and cast monoliths before removing individual bones has proven valuable for the preservation of taphonomic data and for display purposes. Polyurethane resin combined with plaster is useful for small casts, while polyester resin applied in four layers is the preferred technique for larger casts.
The four layers are composed of: a first thin layer of polyester resin with bone colour; followed by another layer of polyester resin of sediment colour and containing glass microspheres to make it thicker. The third layer is composed of fibre glass chopped strands, and the fourth is composed of fibre glass mats embedded
in plain polyester resin. 3D scanning and digitization techniques where tested for the storage of osteological information of individual bones and proved very promising.

Hayashi, S., Carpenter K., Watabe M., Mateus O., & Barsbold R. (2008).  Defensive weapons of thyreophoran dinosaurs: histological comparisons and structural differences in spikes and clubs of ankylosaurs and stegosaurs. Journal of Vertebrate Paleontology. 28(3, Supplement), 89A-90A., Number Suppl. to 3 Abstracthayashi_et_al_2008_histology_stegosaurs_defensive_weapons_of_thyreophoran_dinosaurs-_histological_comparisons_and_structural_differences_in_spikes_and_clubs_of_ankylosaurs_and_stegosaurs.pdfWebsite

Thyreophoran dinosaurs have spike- and club-shaped osteoderms probably used for defensive weapons. The structural and histological variations have been little known. Here, we provide the comparisons of the internal structures in defensive weapons of ankylosaurs and stegosaurs, using spikes of a polacanthid (Gastonia) and a nodosaurid (Edmontonia), clubs of ankylosaurids (Saichania and Ankylosauridae indet. from Canada), and spikes of stegosaurids (Stegosaurus and Dacentrurus), which sheds light on understandings of evolutionary history and functional implications of defensive weapons in thyreophorans. In ankylosaurs, the structural and histological features of spikes and clubs are similar with those of small osteoderms in having thin compact bones, thick cancellous bones with large vascular canals, and abundant collagen fibers. A previous study demonstrated that each of three groups of ankylosaurs (polacanthid, nodosaurid, and ankylosaurid) has distinct characteristic arrangements of collagen fibers in small osteoderms. This study shows that spikes and clubs of ankylosaurs maintain the same characteristic features for each group despite of the differences in shapes and sizes. Conversely, the spike-shaped osteoderms in primitive (Dacentrurus) and derived (Stegosaurus) stegosaurids have similar structure to each other and are significantly different from the other types of stegosaur osteoderms (throat bony ossicles and plates) in having thick compact bones with a medullary cavity. These lack abundant collagen fibers unlike ankylosaur osteoderms. The spikes of ankylosaurs and stegosaurs are similar in shape, but their structural and histological features are different in having unique structures of collagen fibers for ankylosaurs and thick compact bones for stegosaurs, providing enough strength to have large spikes and to use them as defensive weapons. Although the shapes of ankylosaur clubs are different from spikes, the internal structures are similar, suggesting that ankylosaurs maintain similar structures despite of different shapes in osteoderms. These results indicate that ankylosaurs and stegosaurs used different strategies independently to evolve defensive weapons.