Höganäs Formation

Vallåkra Member

This member represent the basal part of the Formation, that represents a transition between the terrestrial Kågeröd Formation and the delta dominated coal layers of the Bjuv Member, being made by poorly stratified clay & claystone, mostly green in coloration.^[7] The sediments of this member are exposed mostly in the quarry of the town of the same name, where is subdivided on the next levels: 6 m of mixed layers, whose composition includes material seen both on the Kågeröd Formation and this member (red clay and 5 m light clay, 3 m argillaceous sandstone and l m dark clay and several layers composed by Spherosiderite).^[7] The uppermost levels are covered by the coal seams of the Bjuv Member. This member has been considered as of Middle and Upper Rhaetian in age.^[7][8]

Bjuv Member

The second member is the Bjuv Member, known as the most fossiliferous one, that was known originally as the Gruv Member (gruva= mine).^[8][9] Coal and clay have been mined in this area since the fifteenth century, being this intensive mining one of the main reasons the fossiliferous layers have provided such a diverse flora. The Bjuv member is divided on two different seams, the B seam, that overlies the older member and the A seam, that marks the limit with the Helsingborg Member.^[8] This layer has a thickness of around 37.22 and 45.72 m in bore No. 256 (stored at the Höganäs Company in Bjuv) from the Bjuv area.^[7] The layer is dominated by coarse arenaceous sediments, specially between Billesholm and Höganäs, parallel to the Söderåsen and Kullaberg horsts.^[9] Towards the southern part of this area the deposition changes, with an increased abundance of argillaceous contents, specially at places like Skromberga.^[9] The age of this member is considered to be Latest Rhaetian and maybe Lower Hettangian. Thus the member records the Triassic–Jurassic extinction, what is seen in the plant oscillations.^[10] The Plant fossils found at this layer are one of the main fossil material of the whole Mesozoic in Sweden, composed by more than 110 species, one of the most complete floras of the same age from any location.^[8][11] The main reason for this datation where suggested due to the presence of the plants Lepidopteris ottonis and Thaumatopteris shenki, as well palynological samples that suggested a Middle Rhaetian age (the Rhaetipollis-Limbosporites Miospore Zone).^[12] Latter works have fount that the Dinosaur Footprint layers spam between the Rhaetian-Hettangian boundary.^[13][14] Beyond the exceptional flora, the member is also known for fossils of Molluscs, arthropods and fish remains.^[8] In the uppermost sequence the deposition changes from a coastal swamp with abundant evidence of plant colonization to fully marine conditions, evidenced by dinoflagellate cysts, recording thus the Rhaetian maximum flooding.^[15]

Helsingborg Member

The Uppermost member of the formation is entirely of Hettangian age, and is the last layer before the start of the deposition of the younger dominant marine Rya Formation.^[7] This member is dominated by Deltaic sediments, along several marine interealatians are frequent, with deposition of coarse, in some cases arkosic sandstones in between more fine-grained deposits may indicate Early Kimmerian tectonic movements.^[16] The member has a maximunn thickness of 215 m and is divided in 2 parts: Höllviken No. 2 indicated that the lower part starts with up to 12 m of kaolinitic clay succeeded by a 15–20 m thick sequence of cross-bedded arkoses and light-coloured clays, being called Boserup beds or Thaumatopteris schenki zone (Pinuspollenites-Trachysporites Miospore Zone).^[17][18] This beds are known from Boserup, but also from the central part of Helsingborg, the Köpinge No. 3 bore and even extent to the Höganäs region (northwest to Eslöv in the south).^[8] This beds are overlain by some metres of arenaceous clays, iron claystone and calcareous sandstone with few intercalation of a coal seam (known as Tågaborg coal seam), where floral remains are also recovered such as Dictyophyllum nilssoni and Equisetites spp.^[8][14] Then the layers turn into 5 m of argillaceous sandstone and 5 m slightly arenaceous clays, with a last 1 m of calcareous sandstone, on a sequence known from cliff series at Laröd-Sofiero at the north of Helsingborg, with plant remains such as Nilssonia polymorpha and Dictyophyllum nilssoni, referred to the Pinuspollenites-Trachysporites zone.^[7] It also appears on Rosendal, Fleninge, Farhult and Klappe.^[7] Helsingborg (Vossbäumer I 969). There is a coal seam, Tinkarpsflötsen, in the middle part of the sequence. The upper part of the Helsingborg Member starts with a 28 m thick sandstone, with a section known as Fleninge beds, that represent layers where marine ingressions were more common, with the last layers of the formation made up of sandstone, claystone and several minor coal seams.^[7]

Ichnofossils

Annelida

More information Genus, Species ...

Genus	Species	Stratigraphic position	Member	Material	Notes	Images
Burejospermum[20]	B. crassitestum	Bjuv	Bjuv member	Cocoons	Freshwater Clitellata Cocoons (Oligochaeta and Hirudinea).
"Cycadeospermum"[20]	"C." sp.	Bjuv	Bjuv member	Cocoons
Dictyothylakos[20]	D. pesslerae D. sp.	Bjuv	Bjuv member	Cocoons

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Mollusks

More information Genus, Species ...

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Avicula[21]	A. nilssoni	Rosendal Farhult Oregården Klappe	Bjuv member Helsingborg member	Shells	An Oyster member of Pteriidae
Cardinia[7]	C. ingelensis	Rosendal Farhult Oregården Klappe	Bjuv member Helsingborg member	Shells	A Clam member of Cardiniidae inside Carditida.
Ceratomya[22]	C. stensioei	Hyllinge	Bjuv member	Shells	A piddock member of Ceromyidae.
Cercomya[22]	C. carlsoni	Bjuv	Bjuv member	Shells	A piddock member of Ceromyidae.
Chemnitzia[22]	C. sp.	Vallåkra	Vallåkra Member	Shells	A sea snail member of Turbonillinae.
Eutrapetzium[7][22]	E. pullastra E. hyllingense	Rosendal Farhult Hyllinge Oregården Klappe	Bjuv member Helsingborg member	Shells	An Oyster member of Ostreidae. The local material assigned to this genus is now lost
Gervillia[21][22]	G. angelini G. praecursor	Rosendal Farhult Oregården Klappe Vallåkra	Vallåkra Member Bjuv member Helsingborg member	Shells	An Oyster member of Bakevelliidae
Liostrea[7][21]	L. hisingeri	Bjuv Rosendal Farhult Oregården Klappe Helsingborg	Bjuv member Helsingborg member	Shells	An Oyster member of Ostreidae . The most common Bivalve found locally.
Mesodesma[21]	M. germari	Rosendal Farhult Oregården Klappe	Bjuv member Helsingborg member	Shells	A Clam member of Mesodesmatidae inside Venerida.
Modiolus[7][22]	M. hoffinanni M. minutus M. sp.	Farhult Klappe Helsingborg Oregården Rosendal Skromberga Svanebeck	Bjuv member Helsingborg member	Shells	A Mussel member of Mytilidae.
Mya[21]	M. ovalis M. elongatus	Rosendal Farhult Oregården Klappe	Bjuv member Helsingborg member	Shells	A Clam member of Myidae inside Myida.
Pecten[22]	P. sp.	Vallåkra	Vallåkra Member	Shells	A scallop member of Pectinidae.
Pleuromya[21][22]	P. aquarum P. suevica	Rosendal Farhult Oregården Klappe Skromberga Vallåkra	Vallåkra Member Bjuv member Helsingborg member	Shells	A Clam member of Pleuromyidae inside Myida.
Protocardia[21][22]	P. eicaldi P. praecursor P. rhaetica P. suecica P. sp.	Rosendal Farhult Oregården Klappe Vallåkra	Vallåkra Member Bjuv member Helsingborg member	Shells	A Clam member of Protocardiinae inside Carditida.
Venerupis[21]	V. elongala V. herberti	Rosendal Farhult Oregården Klappe	Bjuv member Helsingborg member	Shells	A Clam member of Veneridae inside Venerida.

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Insecta

More information Genus, Species ...

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Angelinella[23]	A. angelini	Höganäs	Bjuv member	Elytrons	A beetle, incertae sedis Archostemata
Heeriaopsis[23]	H. laevigatum	Höganäs	Bjuv member	Elytrons	A beetle, incertae sedis Archostemata
Nannocurculionites[23]	N. carlsoni	Bjuv	Bjuv member	Elytrons	A beetle, incertae sedis Archostemata. Originally identified as Curculionites carlsoni
Parabuprestites[23]	P. rugulosus	Bjuv	Bjuv member	Elytrons	A Beetle, member of the family Cupedidae. Originally identified as Buprestites rugulosus
Pseudocarabites[23]	P. deplanatus	Bjuv	Bjuv member	Elytrons	A Beetle, member of the family Carabidae. Originally identified as Carabites deplanatus.
Pseudohydrophilites[23]	P. nathorsti	Bjuv	Bjuv member	Elytrons	A Beetle, member of the family Schizocoleidae. Originally identified as Hydrophilites nathorsti.

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Fish

More information Genus, Species ...

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Hybodus[24]	H. sp.	Helsingborg	Helsingborg member	Isolated Teeth	A freshwater/marine member of Hybodontidae.
Hyllingea[25]	H. swanbergi	Hyllinge	Bjuv member	Two flattened fossils, both almost 62 cm in length.	A freshwater member of the family Acrolepidae or Ptycholepiformes.
Lissodus[24]	L. sp.	Helsingborg	Helsingborg member	Isolated Teeth	A freshwater/marine member of Lonchidiidae.
Palaeoxyris[26]	P. muensteri	Bjuv Helsingborg	Bjuv member Helsingborg member	Shark eggs Capsules	Freshwater shark egg capsule associated with Neocalamites, likely produced by members of Hybodontidae.[26]
Parvodus[24]	P. sp.	Helsingborg	Helsingborg member	Isolated Teeth	A freshwater/marine member of Lonchidiidae.
Saurichthys[22]	S. acuminatus	Bjuv	Bjuv member	Specimen preserved in an slab; referred scales & Teeth	A freshwater member of the family Saurichthyidae.
Scanilepis[27]	S. dubia	Bjuv	Bjuv member (Rhaetian)	Almost complete large (110 cm); Isolated specimen (200 cm) which is a counter-impression	A freshwater member of the family Scanilepididae.
Semionotus[22]	S. nilssoni	Bjuv Boserup	Bjuv member	Specimen preserved in an slab; referred scales & Teeth	A freshwater member of the family Semionotidae.

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Amphibia

More information Genus, Species ...

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Gerrothorax[28]	G. pulcherrimus	Coal-mine at Bjuv	Bjuv member	LU 3176T, LU 3176aT, LU 3176bT, postcrania including interclavicles and clavicles, vertebrae and osteoderms; referred NR B2–4, partial skull & NR B18a, b, c, d, e, postcranial remains	An amphibian, member of the family Plagiosauridae.

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Amniotes

Tracks discovered in the Höganäs Formation have been assigned to the ichnogenus Grallator (Eubrontes) cf. giganteus, which were discovered in Rhaetian strata, and Grallator (Eubrontes) soltykovensis, which were discovered in Hettangian strata.^[29] A few of the tracks were taken to museums, but most of them disappeared in natural floodings.^[29]

After the end of a seven-year excavation project at Billesholm, researchers announced on 13 October 2022 the identification of seven dinosaur species based on fossil remains, out of which three species were new to science.^[30] The fossils are yet to be analyzed and scientifically published.^[31] Overall 8000 finds include footprints of both carnivorous and herbivorous dinosaurs and 4 tonnes of fossil material that went to Uppsala.^[31]

More information Genus, Species ...

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Dinosauria? indet.[32]	Indeterminate	Höganäs mine	Helsingborg member	Vertebral column (not collected)	Incertae sedis
Eubrontes[29][33]	E. giganteus	Gustaf Adolf mine Helsingborg tunnel Höganäs Bjuv	Bjuv Member (Rhaetian)	Footprints	Eubrontes tracks were likely made by Dilophosaurus-like theropods.
Kayentapus[13][29][34]	K. soltykovensis	Southern quarry at Vallåkra	Helsingborg Member (Hettangian)	Footprints	The footprints are small-sized, tridactyl and relatively narrow. Likely made by Coelophysidae-like dinosaurs.
Plesiosaur? indet.[32]	Indeterminate[2]	Billesholm mine	Helsingborg member	4 dorsal vertebrae	Suggested to be an indeterminate small theropod or a mistaken Plesiosaur.
Thyreophora? indet.[35]	Indeterminate	Gustaf Adolf mine	Bjuv Member (Rhaetian)	Footprints	Suggested that it was left by an early advanced thyreophoran dinosaur, in this case the earliest known.

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