The Mawson Formation is a geological formation in Antarctica, dating to roughly between 182 and 177 million years ago and covering the Toarcian faunal stage of the Jurassic Period in the Mesozoic Era. Vertebrate remains are known from the formation. The Mawson Formation is the South Victoria Land in the Ross Dependency equivalent of the Karoo Large Igneous Province in South Africa (including the upper Clarens Formation desertic interbeds), as well the Lonco Trapial Formation and the Cañadón Asfalto Formation of Argentina. The Volcanic material was likely sourced from the Antarctic Peninsula´s Ellsworth Land Volcanic Group.
Sedimentary interbeds deposited over lava flows of the Kirkpatrick Basalt during the Early Jurassic splitting of Gondwana represent unusual freshwater paleoenvironments, with hotter conditions that allow to the diversification of the microbes (Archea).
According to Barrett, "...the basalt-dominated Mawson Formation and tholeiitic flows (Kirkpatrick Basalt)...are included in the Ferrar Group." The Mawson Formation consists of , breccia, and lahar, evidence of magma entering water-saturated . The Kirkpatrick Basalts (180 Megaannum) have interbedded lake sediments with plant and fish fossils.
Geology
Paleoenvironment
Fossil content
Demospongiae
Demospongiae|style="background:#FEF6E4;" Indeterminate|style="background:#FEF6E4;"
|style="background:#FEF6E4;"All the sections|style="background:#FEF6E4;" Borings in invertebrate valves|style="background:#FEF6E4;" Holes of random pattern in valves. Boring Traces on local Conchostracan valves are common and suggested to resemble the boring traces of extant sponges, yet there isn't any evidence of Porifera fossils in the local beds|style="background:#FEF6E4;"
Crustacea
Carapacestheria
All the Sections Carapaces A Freshwater member of Diplostraca (Spinicaudatan). Related to the modern Cyzicus mexicanus and recovered in siliclastic interbeds, representing the most common fossil animal in the unit. Cornia
All the Sections Carapaces A Freshwater member of Diplostraca (Spinicaudatan). Represents the only Jurassic Records of the genus, know mostly from Permian and Triassic deposits, being a possible relict genus. Specimens recovered show different variations in coloration, what can indicate effects of hydrothermal influence on either the living animal or the dead carapace. Darwinula
All the Sections Valves Common Early Jurassic Freshwater Ostracoda. The specimens of this genus cannot be identified to species level, yet bear resemblance with specimens from the same age of South Africa, as well as Triassic specimens from India. Isopodichnus|style="background:#FEF6E4;"
|style="background:#FEF6E4;"
|style="background:#FEF6E4;"All the sections|style="background:#FEF6E4;" Braided Structures|style="background:#FEF6E4;" Freshwater tubular braided Structures. Interpreted as traces of crustaceans searching for food in the lacustrine bottom|style="background:#FEF6E4;" Lepidurus
All the Sections Complete Specimens A Freshwater member of Notostraca. Represented by specimens much bigger than forms (20 mm compared with smaller 10–12 mm breadth) from South Africa Lioestheria
All the Sections Carapaces A Freshwater member of Diplostraca (Spinicaudatan). Correlated with coeval East African and Indian lioestheriids Protamphisopus
All the Sections Complete Specimens A Freshwater member of Isopoda. Shows affinities with specimens from the Upper Triassic of New South Wales Scoyenia|style="background:#FEF6E4;"
|style="background:#FEF6E4;"
|style="background:#FEF6E4;"All the Sections|style="background:#FEF6E4;" Burrows|style="background:#FEF6E4;" Burrow fossils in lacustrine environment, probably made by arthropods|style="background:#FEF6E4;" SyncaridaInderminate
All the Sections Complete Specimens A Freshwater member of Syncarida.
Arachnida
Oribatida|style="background:#FEF6E4;" Indeterminate|style="background:#FEF6E4;" Storm Peak|style="background:#FEF6E4;" Middle Section|style="background:#FEF6E4;" Excavated areas filled with coprolites|style="background:#FEF6E4;" Mite traces, incertae sedis inside Oribatida. The tunnels where recovered in wood stems, fern rhizomes and petioles.|style="background:#FEF6E4;"
Insects
Blattaria Indeterminate Carapace Nunatak
SW Gair Mesa Middle Section
Indeterminate Blattaria Cockroaches Caraphlebia C. antartica Carapace Nunatak Middle Section Wings A dragonfly of the family Selenothemidae. Was found to be related with the genus Liassophlebia, but the hind wing has severalweak antenodals in addition to the two strong, primary ones. Coleoptera Indeterminate Carapace Nunatak Middle Section Charred fragmentary beetle elytron A Beetle with resemblance with archostematids (Schizophoridae, Catiniidae) and some adephagian beetles (Hygrobiidae, Amphizoidae) that have such elytra Ephemeroptera Indeterminate Carapace Nunatak Middle Section Abdominal segments and paired cerci Indeterminate Mayfly nymphs Hemiptera Indeterminate Carapace Nunatak Middle Section Abdominal segments and isolated wings Indeterminate Hemipterans
Fish
Archaeomaenidae Indeterminate
Middle Section
A Freshwater member of Archaeomaenidae. Oreochima O. ellioti
Middle Section
A Freshwater archaeomaenidae. One of the few fishes from this family recovered outside Australia, represents a genus that likely lived linked with Hydrothermal settings and was very proliferous on the local lacustrine systems. Represents a rather small genus.
Fungi
Ceratocystis?|style="background:#D1FFCF;" Indeterminate|style="background:#D1FFCF;" Carapace Nunatak|style="background:#D1FFCF;" Middle Section|style="background:#D1FFCF;" Hyphae|style="background:#D1FFCF;" Parasitic Fungus, probably of the family Ceratocystidaceae. Infestation traces and fungal parasitic interaction on several plants. The morphology shown by this hypae and the colonization pattern in the woods resemble that of the extant Verticicladiella wageneri.|style="background:#D1FFCF;" Fungi|style="background:#D1FFCF;" Indeterminate|style="background:#D1FFCF;" Carapace Nunatak|style="background:#D1FFCF;" Middle Section|style="background:#D1FFCF;" Hyphae|style="background:#D1FFCF;" Parasitic Fungus of uncertain relationships. Infestation traces of thick-walled hypae where recovered on Brachyphyllum-type foliage locally|style="background:#D1FFCF;" Fungi Traces?|style="background:#FEF6E4;" Indeterminate|style="background:#FEF6E4;"
|style="background:#FEF6E4;"Middle Section|style="background:#FEF6E4;"
|style="background:#FEF6E4;"Galleries of an infesting organism in conchostracan valves|style="background:#FEF6E4;"
Palynology
Alisporites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Pollen| style="background:#D1FFCF;" Affinities with the families Caytoniaceae, Corystospermaceae, Peltaspermaceae, Umkomasiaceae and Voltziaceae| style="background:#D1FFCF;" Aratrisporites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Spores| style="background:#D1FFCF;" Affinities with Pleuromeiales. The Plueromeiales were tall (2 to 6 m) common in the Triassic. These spores probably reflect a relict genus.| style="background:#D1FFCF;" Araucariacites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Pollen|style="background:#D1FFCF;" Affinities with the family Araucariaceae in the Pinales. Conifer pollen from medium to large arboreal plants.
. Callialasporites'' may come from a related plant]] Baculatisporites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Spores|style="background:#D1FFCF;" Affinities with the family Osmundaceae in the Polypodiopsida. Near fluvial current ferns, related to the modern Osmunda regalis.
specimens; Todisporites'' probably come from similar genera or maybe a species from the genus]] Callialasporites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Pollen|style="background:#D1FFCF;" Affinities with the family Araucariaceae in the Pinales. Conifer pollen from medium to large arboreal plants.
Cibotiumspora| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Spores| style="background:#D1FFCF;" Affinities with Cyatheaceae and Dicksoniaceae inside Filicopsida.| style="background:#D1FFCF;" Classopollis| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Pollen|style="background:#D1FFCF;" Affinities with Cheirolepidiaceae inside Pinales.
Contignisporites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Spores|style="background:#D1FFCF;" Affinities with the Pteridaceae in the Polypodiopsida. Forest ferns from humid ground locations.
specimens; Contignisporites'' probably come from similar genera or maybe a species in the genus]] Corollina| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Pollen|style="background:#D1FFCF;" Affinities with Cheirolepidiaceae inside Pinales.
Cupressacites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Pollen|style="background:#D1FFCF;" Affinities with Cupressaceae.
Cyathidites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Spores| style="background:#D1FFCF;" Affinities with the family Cyatheaceae or Adiantaceae. Arboreal fern spores.| style="background:#D1FFCF;" Dictyophyllitides| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Spores| style="background:#D1FFCF;" Affinities with the family Schizaeaceae, Dicksoniaceae or Matoniaceae.| style="background:#D1FFCF;" Exesipollenites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Pollen|style="background:#D1FFCF;" Affinities with Araucariaceae or Cheirolepidiaceae inside Pinales.
Ginkgocycadophytus| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Pollen| style="background:#D1FFCF;" Affinities with the family Karkeniaceae and Ginkgoaceae.| style="background:#D1FFCF;" Inaperturopollenites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Pollen|style="background:#D1FFCF;" Affinities with Cupressaceae.
Ischyosporites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Spores| style="background:#D1FFCF;" Uncertain pteridophyte affinities| style="background:#D1FFCF;" Neoraistrickia| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Spores| style="background:#D1FFCF;" Affinities with the Selaginellaceae. Herbaceous lycophyte flora, similar to ferns, found in humid settings.| style="background:#D1FFCF;" Osmundacidites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Spores|style="background:#D1FFCF;" Affinities with the family Osmundaceae in the Polypodiopsida. Near fluvial current ferns, related to the modern Osmunda regalis.
Pinuspollenites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Pollen|style="background:#D1FFCF;" Affinities with the family Pinaceae in the Pinopsida. Conifer pollen from medium to large arboreal plants.
. Pinuspollenites'' maybe come from a related plant]] Podosporites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Pollen| style="background:#D1FFCF;" Affinities with the family Podocarpaceae. Occasional bryophyte and lycophyte spores are found along with consistent occurrences of Podosporites variabilis| style="background:#D1FFCF;" Protohaploxypinus| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Pollen|style="background:#D1FFCF;" Affinities with the family Pinaceae in the Pinopsida. Conifer pollen from medium to large arboreal plants.
Puntactosporites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Spores| style="background:#D1FFCF;" Uncertain peridophyte affinities| style="background:#D1FFCF;" Retitriletes| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Spores| style="background:#D1FFCF;" Affinities with the Lycopodiaceae.| style="background:#D1FFCF;" Sculptisporis|style="background:#D1FFCF;"
|style="background:#D1FFCF;"
|style="background:#D1FFCF;" Spores|style="background:#D1FFCF;" Affinities with the family Sphagnaceae. "Peat moss" spores, related to genera such as Sphagnum that can store large amounts of water.|style="background:#D1FFCF;" Striatella| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Spores|style="background:#D1FFCF;" Affinities with the Pteridaceae in the Polypodiopsida. Forest ferns from humid ground locations.
Todisporites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Spores|style="background:#D1FFCF;" Affinities with the Pteridaceae in the Polypodiopsida. Forest ferns from humid ground locations.
Trilobosporites|style="background:#D1FFCF;"
|style="background:#D1FFCF;"
|style="background:#D1FFCF;" Spores|style="background:#D1FFCF;" Affinities with the genus Dicksoniaceae in the Polypodiopsida. Tree fern spores.|style="background:#D1FFCF;" Verrucosisporites| style="background:#D1FFCF;"
| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Spores| style="background:#D1FFCF;" Uncertain peridophyte affinities| style="background:#D1FFCF;" Vitreisporites|style="background:#D1FFCF;"
|style="background:#D1FFCF;"
|style="background:#D1FFCF;" Pollen|style="background:#D1FFCF;" Affinities with the Caytoniaceae|style="background:#D1FFCF;"
Megaflora
Agathoxylon|style="background:#D1FFCF;"
|style="background:#D1FFCF;"
|style="background:#D1FFCF;" Fossil Wood|style="background:#D1FFCF;" Affinities with Araucariaceae or Cheirolepidiaceae inside Pinales.|style="background:#D1FFCF;" Brachyoxylon|style="background:#D1FFCF;"
|style="background:#D1FFCF;"
|style="background:#D1FFCF;" Fossil Wood|style="background:#D1FFCF;" Affinities with Araucariaceae or Cheirolepidiaceae inside Pinales.|style="background:#D1FFCF;" Brachyphyllum|style="background:#D1FFCF;" B. spp.|style="background:#D1FFCF;" Carapace Nunatak|style="background:#D1FFCF;" Several isolated Branched Shoots|style="background:#D1FFCF;" A member of the family Cheirolepidiaceae. Associated with Classostrobus cones.|style="background:#D1FFCF;" Chimaerostrobus|style="background:#D1FFCF;" C. minutus|style="background:#D1FFCF;" Carapace Nunatak|style="background:#D1FFCF;" Single Pollen Cone|style="background:#D1FFCF;" A conifer pollen cone of uncertain Relationships. Chimaerostrobus is reminiscent of extant Araucariaceae and several extinct taxa such as Kobalostrobus and Voltziales.|style="background:#D1FFCF;" Cladophlebis|style="background:#D1FFCF;" C. oblonga|style="background:#D1FFCF;" Carapace Nunantak|style="background:#D1FFCF;" Isolated Pinnae|style="background:#D1FFCF;" A Fern of the family Osmundaceae. Some specimens where reworked from the Hanson Formation to the Mawson Formation. Linked with the tree fern genus Osmundacaulis|style="background:#D1FFCF;" Classostrobus|style="background:#D1FFCF;" C. elliotii|style="background:#D1FFCF;" Carapace Nunatak|style="background:#D1FFCF;" Five permineralized pollen cones|style="background:#D1FFCF;" A member of the Cheirolepidiaceae. More than five Brachyphyllum-type leaves where found in close association with these cones.|style="background:#D1FFCF;" Coniopteris|style="background:#D1FFCF;" C. hymenophylloides|style="background:#D1FFCF;" Carapace Nunantak|style="background:#D1FFCF;" Isolated Pinnae|style="background:#D1FFCF;" A Fern of the family Polypodiales inside Polypodiidae. Common cosmopolitan Mesozoic fern genus. Recent research has reinterpreted it a Crown group of the Polypodiales (Closely related with the extant genera Dennstaedtia, Lindsaea, and Odontosoria).|style="background:#D1FFCF;" Dictyozamites|style="background:#D1FFCF;" D. sp. cf. minisculus|style="background:#D1FFCF;" Carapace Nunatak|style="background:#D1FFCF;" Leaflets|style="background:#D1FFCF;" A Cycadophyta of the family Bennettitales.|style="background:#D1FFCF;" Elatocladus|style="background:#D1FFCF;" E. confertus|style="background:#D1FFCF;" Carapace Nunatak|style="background:#D1FFCF;" Branched Shoots|style="background:#D1FFCF;" A member of the family Cupressaceae. Related to specimens found in the Middle Jurassic of Hope Bay, Graham Land. Probably represent belong to the Conifer Austrohamia from the Lower Jurassic of Argentina and China.|style="background:#D1FFCF;" Marchantites|style="background:#D1FFCF;" M. mawsonii|style="background:#D1FFCF;" Carapace Nunantak|style="background:#D1FFCF;" Isolated Thalli|style="background:#D1FFCF;" A liverwort of the family Marchantiales. Some specimens where reworked from the Hanson Formation to the Mawson Formation. This liverwort is related to modern humid-environment genera.|style="background:#D1FFCF;" Mixoxylon M. jeffersonii Mt. Fazio, Mesa Range Fossil Wood Spermatophyte Wood, probably related to Bennettitales or Cycadales and previously know only from Cretaceous strata, suggesting the Antarctic Floral Biome appeared already in the Jurassic Nothodacrium| style="background:#D1FFCF;" N. warreni| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Cutinised and fertile material| style="background:#D1FFCF;" A member of the family Voltziales. A genus with Resemblance with the extant Dacrydium that was referred to Podocarpaceae, yet a more recent work found it to be just a convergently evolved relative of Telemachus.| style="background:#D1FFCF;" Otozamites| style="background:#D1FFCF;" O. antarcticus| style="background:#D1FFCF;" Carapace Nunatak| style="background:#D1FFCF;" Leaflets| style="background:#D1FFCF;" A Cycadophyta of the family Bennettitales.| style="background:#D1FFCF;" Pagiophyllum| style="background:#D1FFCF;" P. spp.| style="background:#D1FFCF;" Carapace Nunantak| style="background:#D1FFCF;" Single Branched Shoot| style="background:#D1FFCF;" A member of the Pinales of the family Araucariaceae. Representative of the presence of arboreal to arbustive flora.| style="background:#D1FFCF;" Podostrobus| style="background:#D1FFCF;" P. warrenii| style="background:#D1FFCF;" Carapace Nunatak| style="background:#D1FFCF;" Single cone| style="background:#D1FFCF;" A member of the family Voltziales. Originally assigned to the Cheirolepidiaceae, was later suggested to share affinities with the Podocarpaceae, and then found to be a member of Voltziales. Likely represents the cone of the same conifer that produced the Nothodacrium foliage, as convergently resembles cones from extant Microcachrys and Dacrydium.| style="background:#D1FFCF;" Protocupressinoxylon| style="background:#D1FFCF;" P. spp.| style="background:#D1FFCF;"
| style="background:#D1FFCF;" Fossil Wood| style="background:#D1FFCF;" A member of the family Cupressaceae.| style="background:#D1FFCF;" Polyphacelus| style="background:#D1FFCF;" P. stormensis| style="background:#D1FFCF;" Storm Peak| style="background:#D1FFCF;" Silicified rachides| style="background:#D1FFCF;" A Polypodiopsidan of the family Dipteridaceae. Closely related to Clathropteris meniscoides.| style="background:#D1FFCF;" Zamites| style="background:#D1FFCF;" Z. spp.| style="background:#D1FFCF;" Carapace Nunatak| style="background:#D1FFCF;" Leaflets| style="background:#D1FFCF;" Spermatophyta incertae sedis| style="background:#D1FFCF;"
See also
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