The image depicts one of three bones found in association (featured in one of the video clips) in the lower (Albian) part of the Gearle Siltstone. The bone (assembled from five broken fragments) is identified as the right surangular bone of an ichthyosaur, approximately 4-5 metres in length. As preserved the bone is 16 cm long. The horizontal groove near the base of the bone fits into a ridge on a second bone which, we believe, is a fragment of the angular bone.
Weathered tooth from an ichthyosaur. The teeth of ichthyosaurs were designed to capture smaller prey that could be swallowed whole. The narrow jaws of ichthyosaurs were not designed to withstand violent twisting so these reptiles would not have been able to kill and dismember large prey (unlike saltwater crocodiles).
Articulating surface of a weathered vertebra of an elasmosaur (long-necked plesiosaur) from the lower part of the Gearle Siltstone. The vertebra is almost 9 cm long and would originally have been about 9 cm in diameter as well. The size of the vertebra indicates that it originates from an animal roughly 8 metres in length. It represents the first find of elasmosaurs from the Gearle Siltstone.
A bone of a small turtle, collected from the 95-million-year-old uppermost Gearle Siltstone. This is the first find of a turtle from the Gearle Siltstone. Some marine turtles of Cretaceous age grew to enormous sizes with the dorsal shell (carapace) measuring up to 4 metres in length.
Anterior (front) tooth of a shark called Dwardius, collected from the 105 million-year-old, lower part of the Gearle Siltstone. The population of Dwardius sharks differ from those of named species of the genus so it is possible that we are dealing with a new, undescribed species. Dwardius belong to the same order of sharks as the white shark and grey nurse shark. One of the lobes of the root is broken off. The ‘root’ of a shark tooth is not a root in the strict sense as it is not secured in a deep depression in the jaw.
A perfectly preserved upper lateral tooth from a Dwardius shark (lower part of the Gearle Siltstone). As the sharks of this genus grew larger they developed a massive root, indicating a shift in diet to tougher prey.
Lower jaw tooth of the extinct broadnose sevengill shark Gladioserratus, found in the lower part of the Gearle Siltstone (laid down 105 million years ago). This shark belongs to a group known as the hexanchids. They differ from other sharks in having six or seven gill slits instead of five and by having a single dorsal fin (most sharks have two). One of the living species, the broadnose sevengill shark Notorynchus cepedianus (see image below) occurs in shallow water whereas the rest spend most of their time in deep cold water.
An incomplete tooth from an undescribed, extinct wobbegong-type of shark, collected from the lower part of the Gearle Siltstone. Teeth of this un-named species have also been found in marine rocks of similar age near Kalbarri and in north central Queensland.
Anterior portion of a right palatine tooth plate of the chimaeroid Callorhinchus, collected from the lower part of the Gearle Siltstone. Chimaeroids are the sister group to the elasmobranchs (sharks and rays). Like sharks, chimaeroids have a skeleton of cartilage. Whereas sharks and rays have a highly mobile upper jaw (palatoquadrate), connected to the cartilaginous cranium via ligaments it is fused to the cranium in chimaeroids. The latter have a single opening for the gills on each side behind the skull whereas sharks and rays have separate gill slits for each gill arch.
Tooth plate of the extinct chimaeroid Ptyktoptychion (lower Gearle Siltstone). The genus was originally described from rocks of Albian age (~ 105 million years old) in Queensland. It is a very rare chimaeroid known only from three tooth plates (one from Queensland and two from the Giralia range, Western Australia) so we are much exited about this second find from WA.
Tail-bones of a large bony fish, found in the 95 million years old, uppermost part of the Gearle Siltstone. The bony rods forming the tail are held together with the soft mineral gypsum. The flaky bone texture is typical for fishes and quite different from the spongy bone (underneath a dense outer layer of cortical bone) of marine reptiles like ichthyosaurs, turtles and plesiosaurs. The only large bony fish from the uppermost Gearle Siltstone positively identified at this stage is Pachyrhizodus (image below) based on a diagnostic premaxilla bone.