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37-659: Ashfield Shale is part of the Wianamatta group of sedimentary rocks in the Sydney Basin . It lies directly on contemporaneously eroded Hawkesbury sandstone or the Mittagong formation . These rock types were formed in the Triassic Period . It is named after the Sydney suburb of Ashfield . Some of the early research was performed at the old Ashfield Brickworks Quarry. This rock type

74-738: A family of capitosauroid temnospondyls . Fossils belonging to this family have been found in North America , Greenland , Europe , Asia , and Australia . The family Capitosauridae is synonymous with Mastodonsauridae. Mastodonsaurids were generally large amphibians, with some length estimates ranging from 3 to 6 meters. Some genera, like Mastodonsaurus and Cyclotosaurus were specially large, reaching at least 4 meters or more. Other genera like Parotosuchus and Paracyclotosaurus only reached 2 meters or more in length, but it's still large compared to most modern-day amphibians. Some mastodonsaurids including Parotosuchus were covered in

111-411: A large river delta , which shifted over time from west to east. This is evidenced by the sequence of strata , which clearly show the transition from marine deposits in front of the delta to deposits on land: Ashfield shale was formed from clayey marine sediments. The subsequent Minchinbury Sandstone emerged from beach - Nehrungs Islands. The Bringelly shale became alluvial in a marshy plain deposited on

148-409: A long period of time. Fossils are not common in this stratum, however, fossil bivalves , plants, isopods , insects and amphibians have been recorded. One outstanding example being of a Paracyclotosaurus at St Peters , 2.25 metres long. It is one of the most complete mastodonsaurid skeletons ever recovered. Notobrachyops is a genus of brachyopid temnospondyl amphibian. It is known from

185-432: A scaly skin, unlike the smooth skin of modern-day amphibians , and probably moved with an eel -like motion in the water. Another peculiar mastodonsaurid is Sclerothorax , with unusual features including its elongated neural spines. The neural spines are tallest at the front of the spine. Sclerothorax also has a very large pectoral girdle ; the interclavicle bone is longer than the skull, meaning that Sclerothorax has

222-676: A skull roof impression found in the Ashfield Shale at the old Hurstville Brick Company quarry at Mortdale . The Ashfield Shale has also yielded a shark species, a lungfish species, six species of paleoniscid fish, a species of holostean fish , and a subholostean fish. Order: Family: Family: Family: Family: Family: Order: Order: Unranked taxon: Family: Family: Family: Family: Family: Family: Family: Family: Order: Family: Family: Family: Family: Family: Family: Wianamatta shale The Wianamatta Group

259-400: A wider and shorter skull. Its skull also has an elongated preorbital region compared to other mastodonsaurids. The vertebrae of Stanocephalosaurus are rhachitomous, with a neural arch and a bipartite centrum that is divided into a large, unpaired wedge-shaped intercentrum and smaller paired pleurocentra. In anterior and posterior views, the intercentrum is a dorsally half-ring, surrounding

296-607: Is a lot of known information about the skulls of mastodonsaurids, for example, Stanocephalosaurus , one of the most well-known mastodonsaurids, has a lot of data about its skull. The skull of Stanocephalosaurus has key features characteristic to other temnospondyls, with the most apparent being the flattened shape of its skull roof . The dorsal as well as ventral surfaces of the skull of Stanocephalosaurus have well ornamented honeycombed patterns throughout. Palatal views of skulls in this genus show narrow interpalatal vacuities, as well as paired palatal tusks alternately functioning on

333-507: Is close to the surface are also susceptible to dryland salinity. Groundwater quality can range from fresh to highly saline, with the deeper groundwater generally less saline. Other rock types found in the Sydney Basin include the Narrabeen shale , Mittagong formation , Illawarra Coal Measures , Newcastle Coal Measures, and Shoalhaven Group. Mastodonsauridae Mastodonsauridae is

370-480: Is made up of the following units (listed in stratigraphic order): The Wianamatta Group was derived from the Aboriginal name for South Creek . It was officially established in 1952, fully attested in 1954 and further amended in 1979. The Wianamatta Group is the youngest geological layer member of the Sydney Basin , and therefore lies at the highest point as the highest layer member. It was deposited in connection with

407-517: Is often associated with the Inner West and North Shore of the city. However, it has also been recorded at Penrith , Revesby , Bilpin and Mount Irvine . Ashfield Shale comprises black mudstones and grey shales with frequent sideritic clay ironstone bands . The thickness ranges between 45 and 64 metres. It is 20 metres thick at the Sydney Olympic Site . The chemistry of the rock

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444-403: Is somewhat common within mastodonsaurids. Stanocephalosaurus also has a long, triangular skull which is much longer than broad, and has an elongated preorbital region continuously narrowing anteriorly to an obtuse rounded snout. This type of skull is very similar to that of Mastodonsaurus , which is also triangular in shape. The Stanocephalosaurus has at least 100 straight and conical teeth on

481-526: Is typical of shales, with high iron levels, and some iron sulphide and low calcium levels. The geology of the shale lenses within the Hawkesbury Sandstone is chemically similar to the Ashfield Shale. At Turramurra 33 metres remains and formerly there was a good deep exposure of it at the Railway Station until this suffered shotcreting. Small scale bedding is abundant. The shales are sandy at

518-409: Is yet again, another well-known mastodonsaurid, and just like most genera of the family, it had various species. This mastodonsaurid has at least three species, including its type species , which is P. davidi , along with two other: P. crookshanki and P. morganorum . The completeness of the skeleton of this animal led to an accurate description. The small distortion of the head can be overlooked, and

555-415: The maxilla begins immediately behind and lateral to the nostril and passes straight back to the lachrymal, on which bone it turns outward and forward and ends abruptly. Another groove appears to begin on the maxilla, immediately lateral to that described above. It passes back just above the insertion of the teeth for the full length of the bone. The supraorbital groove begins abruptly on the dorsal surface of

592-399: The premaxilla and maxilla combined, gradually increasing in size towards the front. While there is a lot of known information about Stanocephalosaurus , some of the skull regions which were previously inaccessible or too poorly preserved on Stanocephalosaurus have been observed with X-ray micro-CT scans, including the otic capsule, delta groove of the exoccipital, as well as parts of

629-404: The premaxilla . Like the mentioned Xenotosuchus , the genus Wetlugasaurus is also one of the smaller and less known mastodonsaurids. It had a skull that measured around 22 centimetres (8.7 in), and reached a total length of at least 1 metre (3 ft 3 in), and although it is pretty large compared to modern-day amphibians, Wetlugasaurus is still very small compared to most of

666-414: The vomer and palatine , with the vomerine tusks directed backwards. This animal shows an increased expansion of the pterygoids and palatines, as well as narrow posterior nostrils . The vomer also bears two vomerine rows: a transversal denticle row and a longitudinal denticle row that runs along the inner margin of the choana. The palatines and ectopterygoids are broader than in other temnospondyls, which

703-504: The Ashfield Shale supported a number of quarries. The shale provided a suitable raw material for brickmaking. Sydney soils based on shale are not particularly fertile. But at Parramatta they proved more suitable to agriculture than those at Farm Cove , in the early days of the First Fleet . Ashfield Shale is considered a freshwater lacustrine paleoenvironment . It was gradually inundated by brackish water, then shallow marine waters over

740-479: The Wianamatta Group rocks are generally less saline than the near-surface occurrences. The Wianamatta Group has been inferred to represent a cycle of basin infilling associated with the migration of a large delta front from west to east. The Ashfield Shale was deposited in a low energy marine environment and preserves laminated silty sediments. The Minchinbury Sandstone comprises a set of sandy barrier islands at

777-556: The arterial and nervous system. Air pockets around the stapes of Stanocephalosaurus have been hypothesized to act as resonance chambers, meaning that the spoon-shaped inner ear bone could be related to underwater hearing. This trait is possibly associated with early tetrapod evolution, which probably also appears on other members of this family and can act as a link to anuran tympanum evolution. The narrow head and elongated snout of Stanocephalosaurus suggests that stress levels during biting are slightly higher than temnospondyls with

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814-531: The complete preservation of the skull and jaws makes its shape certain at a length of 60 cm. The right corner of the head is essentially undistorted and shows that the skull at its point of greatest depth is almost exactly as high as the lower jaw. The lower jaw also has its symphysis the same height as the skull above it. Therefore, at its point of greatest height, the head was essentially of oval section, 22 cm high and 44 cm wide. The nostril, orbit and tympanic membrane are all directed upward, but whether

851-596: The construction of the Lane Cove Tunnel was affected by the collapse of an exit ramp excavation, through Ashfield Shale. Difficulties may be encountered where the Ashfield Shale interfaces with the Hawkesbury Sandstone and the Mittagong Formation . Ashfield Shale is associated with the critically endangered Blue Gum High Forest and Sydney Turpentine-Ironbark Forest . In the earlier days of Sydney,

888-543: The delta, meandered through the rivers, and deposited sand at various locations, each of which was narrowly defined, which later solidified into sandstone. Today's weathering of the surface of the existing claystone produces abundant clay, which leads to the formation of clay soils with low water permeability, as they occur, for example, on the Cumberland Plain widespread. Here are Podsol floors widespread that swell when supplying water and shrink during drying. Over

925-414: The distinct adult shape. The head bones are covered in large pits and grooves, indicating extensive dermal armour on the head. Both the upper and lower jaw had tusks , those of the upper jaw being situated on a second row of teeth on the vomer and palatine bone . Contrary to related forms like Mastodonsaurus and Stanocephalosaurus , the tusks of the lower jaw were of moderate size and did not penetrate

962-473: The eye could be projected upward above the head to give a horizontal view similar to a frog , is difficult to determine. With very similar features to Cyclotosaurus , Subcyclotosaurus is another good example of mastodonsaurid. Its skull is characterized by the small tabular without any trace of a "horn", but with a round lappet that approaches the squamosal flange lateral to the tympanic membrane, failing to meet it by about its own width. The occiput between

999-484: The former shoreline. The Bringelly Shale was deposited in a swampy alluvial plain with meandering streams flowing from the west forming discontinuous beds of sandstone. Weathering of the shale units produces a rich clayey soil, often with poor drainage, such as that in the Cumberland Plain . These clay soils are recognised as being reactive with appreciable Shrink-swell capacity . Low-lying areas where groundwater

1036-409: The other mastodonsaurids. Mastodonsaurids were piscivorous , mainly preying on small and mid-sized fish, although they also ate land-living animals, such as small archosaurs . Some evidences, including the fossils of some smaller temnospondyls bear tooth marks made by mastodonsaurid-like animals. It is very likely that mastodonsaurids caught their food like the living Giant Salamander, waiting until

1073-430: The otic notches is proportionately wide, a reflection of the small size of the skull. The skull is otherwise of normal mastodonsaurid structure, being specifically more similar to Parotosuchus than to any other genera of this family. The skull also has a small internasal vacuity between the dorsal processes of the premaxillae and lateral lines are often shown as continuous grooves with well-defined borders. A deep groove on

1110-556: The persistent notochord from ventral and lateral sides. Lateral and ventral surfaces of the intercentrum are smooth, suggesting a continuation of cartilage due to the unfinished medial surface. The posterodorsal margin of the intercentrum also shows a parapophysis for articulation with the capitulum of the ribs. Another well-known mastodonsaurid in terms of fossil knowledge is Mastodonsaurus , notably from numerous skull specimens found in Germany. The large, oval eye sockets are midway along

1147-421: The pitches of the Wianamatta Group, water-bearing layers can form. Deep and large clay deposits of this formation are able to collect groundwater ; however, if they are at or near the surface, salted dry land may form as the water evaporates. The quality of the groundwater over the pitches can be good, so that drinkable water occurs, or it can be very saline and thus not potable. The lower groundwater resources in

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1184-433: The premaxilla, immediately passes on to the nasal, and extends back on that bone close to its suture with the lachrymal. It then comes on to the prefrontal, passing on to the frontal where that bone enters the orbital border. Then as a well-defined groove it surrounds the hinder part of the orbit, turns vertically on to the jugal, and then backward to cross the point where jugal, quadratojugal and squamosal meet, continuing over

1221-426: The proportionally largest interclavicle of any temnospondyl. The body of Sclerothorax is covered by small scale-like bony ossicles that would have been embedded in the dermis in life. The skull of Sclerothorax is short, wide, and roughly rectangular in shape. The snout is wider than the cheek region. The bones along the midline of the skull roof are also very wide relative to those of other temnospondyls. There

1258-424: The shale becomes a paler colour. Weathering of the shale units produces a reddish/brown podsolic soil , often with poor drainage, such as that in the Cumberland Plain . These clay soils are recognised as being reactive with an appreciable shrink-swell capacity . The adjacent Hawkesbury Sandstone is considered a safer bedrock than the (less stable and laminated ) Ashfield Shale for building construction. In 2005,

1295-478: The skull. The jaws are lined with conical teeth, two large tusks project up from the end of the lower jaw, fitting through openings on the palate and emerging out from the top of the skull when the jaw is closed. Based on recent research, the body of Mastodonsaurus was more crocodile-like in shape than in earlier reconstructions, with a longer trunk section and a longer tail. The greatly reduced limb bones have joints that are poorly developed. Paracyclotosaurus

1332-435: The squamosal to pass back on to the body. Xenotosuchus is a member of this which is not very well known, and only a few fragments have been discovered from this animal. This genus was originally a species of Parotosuchus . Like many mastodontosaurids, it was a large animal with a large head. Its amphibian life history meant that the distinct shape of the skull roof would change from a generalized tadpole -like skull to

1369-581: The top of the sequence. There are up to ten bands in a fifteen-metre section. The fine grained silty sediments were laid down in a low energy, south-east flowing deltaic setting, near the shores of a shallow sea. Ashfield Shale underlies the Prospect dolerite intrusion in Pemulwuy . Natural selection in which the Ashfield Shale is completely exposed is rare. However, it can be seen at railway and roadside cuttings, as well as old quarries. With weathering and exposure,

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