Hybodus is an extinct genus of hybodont that lived from the Middle Triassic to the Late Cretaceous periods. Species closely related to the type species Hybodus reticulatus lived during the Early Jurassic epoch. Numerous species have been assigned to Hybodus spanning a large period of time, and it is currently considered a wastebasket taxon that is 'broadly polyphyletic' and requires reexamination.
Hybodontiformes, commonly called hybodonts, are an extinct group of shark-like cartilaginous fish (chondrichthyans) which existed from the late Devonian to the Late Cretaceous. Hybodonts share a close common ancestry with modern sharks and rays (Neoselachii) as part of the clade Euselachii. They are distinguished from other chondrichthyans by their distinctive fin spines and cephalic spines present on the heads of males. An ecologically diverse group, they were abundant in marine and freshwater environments during the late Paleozoic and early Mesozoic, but were rare in open marine environments by the end of the Jurassic, having been largely replaced by modern sharks, though they were still common in freshwater and marginal marine habitats. They survived until the end of the Cretaceous, before going extinct.
The Kota Formation is a geological formation in India. The age of the Kota Formation is uncertain; it is commonly considered to date to the Early Jurassic, but some studies have suggested it may extend into the Middle Jurassic or even later. It conformably overlies the Lower Jurassic Upper Dharmaram Formation and is unconformably overlain by the Lower Cretaceous Gangapur Formation. It is split into a Lower Member and Upper Member. The Lower Member is approximately 100 m thick while the Upper Member is 490 m thick. Both subunits primarily consist of mudstone and sandstone, but near the base of the upper unit there is a 20-30 metre thick succession of limestone deposited in a freshwater setting.
The Posidonia Shale geologically known as the Sachrang Formation, is an Early Jurassic geological formation of southwestern and northeast Germany, northern Switzerland, northwestern Austria, southern Luxembourg and the Netherlands, including exceptionally well-preserved complete skeletons of fossil marine fish and reptiles.
The Aganane Formation is a Pliensbachian geologic formation in the Azilal, Béni-Mellal, Ouarzazate, Tinerhir and Errachidia provinces, central Morocco, being the remnant of a local massive Carbonate platform, and known mostly for its rich tracksites including footprints of thyreophoran, sauropod and theropod dinosaurs. This formation has been dated to the Pliensbachian stage of the Lower Jurassic, thanks to the find of the ammonite Arieticeras cf. algovianum, indicator of Middle Domerian in the upper zone, and lower delimitation by the foraminifers Mayncina termieri and Orbitopsella praecursor. The dinosaur tracksites are all located a few metres below the Pliensbachian-Toarcian limit, being coeval and connected with the lowermost layers of the continental Azilal Formation. The Aganane Formation was also coeval with the Jbel Taguendouft Formation and the Tamadout 1 Formation, all developed along a local "platform-furrow" in the Middle Atlas Mountains, that act as a barrier controlling the western border of the Jurassic Atlas Gulf. The nearshore sections, including both carbonate platforms and close to sea terrestrial facies where located on an isolated internal domain thanks to the control of the barrier, allowing the Aganane Formation to develop on a hot and humid climate, where a local algal marsh had intermittent progradations, intercalated with a layer of terrigenous continental origin. The ichnosites were developed in tidal flats and coastal deposits suitable to sea flooding.
The Hasle Formation is a geologic formation on the island on Bornholm, Denmark. It is of early to late Pliensbachian age. Vertebrate fossils have been uncovered from this formation. The type section of the formation is found at the south of the costal Hasle Town, and it is composed by rusty yellow to brownish siltstones and very fine-grained sandstones. The southernmost arch, Hvjdoddebuen, is not as fossil-bearing as the type unit in Hasle. The formation can be separated in two different petrographic types: type 1 sandstones are friable with layers and lenses of concretionary siderite and type 2 well-cemented sandstones. Both types where deposited in a relatively high-energy marine environment with a diagenetic pattern that demonstrates a close relation to various phases of subsidence and uplift in the tectonically unstable Fennoscandian Border Zone. Most of its deposition happened on a storm-dominated shoreface, with the exposed parts deposited in an open marine shelf within 1–2 km distance from the fault-controlled coastlines. However, recent works have recovered terrestrial fauna from it, including a footprint, suggesting easterly winds and low tide could have exposed the inner parts of the upper shoreface, and create long-lasting Floodplain-type environments. Field works since 1984 have shown a mostly hummocky cross-stratified deposition, with great complexity of the sediments that suggests very complicated and variable flow conditions, with Megaripples derived from storm events. Storms were frequent and the coastline faced a wide epeiric sea with a fetch towards the west of possibly 1000 kilometers. The Jamesoni–Ibex Chronozone in the Central European Basin represents a clear sea Transgression, due to the appearance of ammonites from Thuringia and southern Lower Saxony, showing a full marine ingression towards the west. This rise in the sea level is also measured in the north, as is proven by the presence of Uptonia jamesoni in Kurremölla and Beaniceras centaurus plus Phricodoceras taylori on the Hasle Formation. The whole Hasle Sandstones are a result of this rise in the sea level, where the marine sediments cover the deltaic layers of the Rønne Formation. The rise in the sea level is observed on palynology, as on the Hasle Formation Nannoceratopsis senex (Dinoflajellate) and Mendicodinium reticulaturn appear, indicating a transition from paralic and restricted marine to fully marine.
Seppo is an extinct genus of spiders, possibly of the superfamily Palpimanoidea, that lived about 180 million years ago, in the Early Jurassic of what is now Europe. The sole species Seppo koponeni is known from a single fossil from Grimmen, Germany. With the scorpion Liassoscorpionides, it is one of the two only known arachnids from the Lower Jurassic of Germany. Seppo is the first unequivocal Early Jurassic spider, and was recovered from the Green Series member of the Toarcian Ciechocinek Formation.
The Drzewica Formation is a geologic formation in Szydłowiec, Poland. It is Pliensbachian in age. Vertebrate fossils have been uncovered from this formation, including dinosaur tracks. The Drzewica Formation is part of the Depositional sequence IV-VII of the late lower Jurassic Polish Basin, with the IV showing the presence of local Alluvial deposits, with possible meandriform deposition origin, dominated in Jagodne and Szydłowiec, while delta system occurred through the zone of the modern Budki. The sequence V shows a reduction of the erosion in the Zychorzyn borehole of the Drzewica Formation, showing changes on the extension of the marine facies, where upper deposits change from Alluvial to Deltaic-Seashore depositional settings. VI-VII facies were recovered on the Brody-Lubienia borehole, with a lower part exposed on the village of Śmiłów that shows a small fall of the Sea level. The stathigraphic setting of the dinosaur tracks reported from the formation suggest a Seashore or Deltaic barrier. Body fossils reported include bivalves, palynology, fossil trunks, roots. Trunks of coniferous wood, especially Cheirolepidiaceae and Araucariaceae trees show the occurrence of vast coniferous forests around the tracksite. The association of forests and dinosaur megafauna on the Pliensbachian suggests also a colder and specially dry ecosystem. Drzewica deposits where in part to be a gigantic shore barrel, setting at the time where the Polish basin sea was at its lowest point. Other related units are Fjerritslev or Gassum Formation, Hasle & Sorthat Formation (Bornholm), upper Neringa Formation (Lithuania) and abandoned informal units in other regions of Poland: upper Sawêcin beds, Wieluñ series or Bronów series.
The Ciechocinek Formation, known in Germany as the Green Series/Grimmen Formation is a Jurassic geologic formation that extends across the Baltic coast, from Grimmen, Germany, to Lithuania, with its major sequence in Poland and a few boreholes in Kaliningrad. It represents the largest continental area defined as deltaic in the fossil record, estimated to cover ~7.1 × 100,000 km2 (39,000 sq mi) only in the Polish realm. It is mostly known for its diverse entomofauna, composed of more than 150 species of different groups of insects, as well as its marine vertebrate fossils, including remains of sharks, actinopterygians and marine reptiles, along with terrestrial remains of dinosaurs, including the early thyreophoran Emausaurus and others not yet assigned to a definite genus. Its exposures are mostly derived from active clay mining of a dislocated glacial raft with exposed Upper Pliensbachian to late Toarcian shallow-marine sediments. Starting with coarse and fine sand deposits with concretions, the pure clay of the Ciechocinek Formation, after the falciferum zone, was deposited in a restricted basin south of the Fennoscandian mainland. It hosts a layer full of carbonate concretions, where a great entomofauna is recovered.
The Ciechocinek Formation is a Jurassic geologic formation which extends across the Baltic coast from Grimmen, Germany, to Nida, Lithuania, with its major sequence in Poland and boreholes in Kaliningrad. Dinosaur species uncovered here, including Emausaurus and other unclassified genus.
The Blanowice Formation is a geologic formation in Częstochowa, Poland. It is late Pliensbachian-Lowermost Toarcian age. Plant fossils have been recovered from this formation. Along with the Drzewica Formation is part of the Depositional sequence IV-VII of the late lower Jurassic Polish Basin. Deposits of sequences IV, V, VI and VII make up the Blanowice Formation, being all four sequences are of Pliensbachian age, documented by megaspores (Horstisporites). On the upper strata, “sub-coal beds" cover the sequence VII-lower VIII, while the uppermost part of VIII is identified with the Ciechocinek Formation. The Blanowice Formation has been known for decades thanks to the abundant plant fossils and plant roots, but mostly due to the Blanowice Brown Coals, where the oldest Biomolecules found worldwide have been recovered. The Mrzygłód mine dinocyst assemblage is taxonomically undiversified, containing specimens that are good age indicators allowing relatively precise suggestion of its age. Luehndea spinosa, with a single recovered specimen spans between the Late Pliensbachian (Margaritaus) to the Lowermost Toarcian (Tenuicostatum). Other ocal dinocysts such as Mendicodinium range Late Pliensbachian–Aalenian, a wider stratigraphic range. The lower part of the formation is coeval in age with the Gielniów Formation and Drzewica Formation, Lobez Formation and Komorowo Formation (Pomerania), Olsztyn Formation, the lower part of the Rydeback Member of the Rya Formation, lower Fjerritslev or Gassum Formation, lower and middle Sorthat Formation (Bornholm), Neringa Formation (Lithuania). The upper part is coeval with the lowermost upper Rydeback Member, upper Gassum Formation and lower Lava Formation (Lithuania).
The Sorthat Formation is a geologic formation on the island of Bornholm, Denmark and in the Rønne Graben in the Baltic Sea. It is of Latest Pliensbachian to Late Toarcian age. Plant fossils have been recovered from the formation, along with several traces of invertebrate animals. The Sorthat Formation is overlain by fluvial to lacustrine gravels, along with sands, clay and in some places coal beds that are part of the Aalenian-Bathonian Bagå Formation. Until 2003, the Sorthat Formation was included as the lowermost part of the Bagå Formation, recovering the latest Pliensbachian to lower Aalenian boundary. The Sorthat strata reflect a mostly marginally deltaic to marine unit. Large streams fluctuated to the east, where a large river system was established at the start of the Toarcian. In the northwest, local volcanism that started in the lower Pliensbachian extended along the North Sea, mostly from southern Sweden. At this time, the Central Skåne Volcanic Province and the Egersund Basin expelled most of their material, with influences on the local tectonics. The Egersund Basin has abundant fresh porphyritic nephelinite lavas and dykes of lower Jurassic age, with a composition nearly identical to those found in the clay pits. That indicates the transport of strata from the continental margin by large fluvial channels of the Sorthat and the connected Röddinge Formation that ended in the sea deposits of the Ciechocinek Formation green series.
The Rya Formation is a geologic formation in Skåne County, southern Sweden. It is Early to early Middle Jurassic in age. The Rya Formation comprises siltstones, claystones, sandstones, mudstones and rare coal beds. The formation overlies the Höganäs Formation and is overlain by the Vilhelmsfält and Mariedal Formations.
The Gram Formation is a geological formation in Gram, Denmark. It preserves fossils dating from the Miocene period. The formation consists of three layers: the glauconite-rich, the Gram Clay, and the Gram sand. The sediments in the formation were deposited in an open marine depositional environment known as the Gram Sea.
Agaleus is an extinct genus of stem-galeomorph shark from the Early Jurassic Epoch. The genus Agaleus is monotypic, consisting solely of the species Agaleus dorsetensis. This species is currently only known from isolated teeth. It is the oldest known unambiguous crown group shark.
The Borucice Formation, also known in older literature as the Borucice Series, is a Jurassic geologic formation that extends to nearly whole of Poland. This formation represents the last sequence of the lower Jurassic in Poland, recovering the depositional sequences IX and X, and may even recover lowermost parts of the first Middle Jurassic sequence. It represents mostly a series of alluvial depositional systems with subordinate intervals of deltaic deposits. Dinosaur Tracks are among the fossils that have been recovered from the formation. Most of the sediments of the Polish realm come from deltaic, fluvial and marine deposits. It mainly consists of light whitish-grey, fine grained sandstones interbedded by clay containing plant detritus and minute fragments of coal. It also has dark grey mudstones with marine lamellibranches and an Upper Lias microfauna. Its main equivalents are the Jurensismergel Formation of Germany, upper part of the Rya Formation and the uppermost Sorthat Formation (Bornholm). There are also coeval abandoned informal units in Poland: Upper Lisiec beds, or the Kamień Beds.
The Djupadal Formation is a geologic formation in Skåne County, southern Sweden. It is Early Jurassic in age. It is part of the Central Skåne Volcanic Province, know by the discovery of basalt tuff layers, including Sandåkra, Korsaröd and Djupadal.
The Röddinge Formation is a geologic formation in Skåne County, southern Sweden. It is Early Jurassic (Sinemurian-Toarcian) in age. It is a unit with a limited degree of exposure, being identified mostly by its deposits on the Fyledalen Fault Zone, specially on Kurremölla, where is present the main fossil deposit. It is a unit known mostly for large museum collections and estimated to have a thickness of several hundreds of meters. It is also known for its large iron deposits. It is correlated with the mostly marine Rya Formation of western Skåne County, the Volcanic deposits of the Djupadal Formation and specially the Sorthat Formation of Bornholm. Most likely, the coarse-grained nature of the Röddinge Formation is linked to rapid erosion of a tectonically active hinterland.
The Höör Sandstone is a geologic formation in Skåne County, southern Sweden. It is Early Jurassic (Hettangian-Pliensbachian) in age. This unit outcrops in central Skane on a few isolated exposures, being traditionally subdivided into the lower “millstone” (“kvarnstenen”) and the upper “buildingstone”. The lowermost layers where also claimed to host Rhaetian strata, however latter works suggested that the layers devolved as red beds, were part of the new Hörby Formation, thus delimitating the Höör sandstone to the lower Jurassic. It has been assumed to be limited to Hettangian-Sinemurian layers, yet recent palynological analysis suggest the uppermost section is of Pliensbachian age, underlying and maybe interacting with the younger volcanic deposits. The Höör sandstone represents a mostly fluvial unit with a rich collection of fossil plants, yet also includes brackish bivalves in some layers, pointing to marine ingressions locally.
The Tafraout Group is a geological group of formations of Toarcian-Aalenian age in the Azilal, Béni-Mellal, Imilchil, Zaouiat Ahansal, Ouarzazate, Tinerhir and Errachidia areas of the High Atlas of Morocco. The Group represents the remnants of a local massive Siliciclastic-Carbonate platform, best assigned to succession W-E of alluvial environment occasionally interrupted by shallow marine incursions and inner platform to open marine settings, and marks a dramatic decrease of the carbonate productivity under increasing terrigenous sedimentation. Fossils include large reef biotas with richness in "lithiotid" bivalves and coral mounts, but also by remains of vertebrates such as the sauropod Tazoudasaurus and the basal ceratosaur Berberosaurus, along with several undescribed genera. While there have been attributions of its lowermost layers to the Latest Pliensbachian, the current oldest properly measured are part of the Earliest Toarcian regression ("MRST10"), part of the Lower-Middle Palymorphum biozone. This group is composed of the following units, which extend from west to east: the Azilal Formation ; the Amezraï Formation ; the Aguerd-nˈTazoult Formation ; the Tafraout Formation & the Tagoudite Formation. They are connected with the offshore Ait Athmane Formation and the deeper shelf deposits of the Agoudim 1 Formation. Overall, this group represents a mixed carbonate-siliciclastic system of several hundred meters thick, dominated by deposits of shallow marine platforms linked to a nearby hinterland dominated by conglomerates. The strata of the group extend towards the central High Atlas, covering different anticlines and topographic features along the mountain range.
