Hubbry Logo
Winton FormationWinton FormationMain
Open search
Winton Formation
Community hub
Winton Formation
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Winton Formation
Winton Formation
Winton Formation
View on Wikipedia
from Wikipedia

The Winton Formation is a Cretaceous geological formation in central-western Queensland, Australia. It is late Albian to early Turonian in age.[2] The formation blankets large areas of central-western Queensland. It consists of sedimentary rocks such as sandstone, siltstone and claystone. The sediments that make up these rocks represent the remnants of the river plains that filled the basin left by the Eromanga Sea - an inland sea that covered large parts of Queensland and central Australia at least four times during the Early Cretaceous period. Great meandering rivers, forest pools and swamps, creeks, lakes and coastal estuaries all left behind different types of sediment.

Key Information

In some areas, the Winton Formation is over 400 metres thick. To bring with them such a huge amount of sediment, the rivers that flowed across these plains must have been comparable in size to the present-day Amazon or Mississippi rivers. As more and more sediment was brought in, the margins of the inland sea slowly contracted. By around 95 million years ago, the deposition was complete and the inland sea would never be seen again.

By virtue of its age and the environmental conditions under which the rocks it consists of were deposited, the Winton Formation represents one of the richest sources of dinosaur fossils anywhere in Australia.

Fauna

[edit]

A fossil footprint-(ichnite), Wintonopus, found with two other dinosaur genera footprints at the Lark Quarry in Australia, c.f. Tyrannosauropus and Skartopus, have been found in the Winton Formation.


Mollusca

[edit]
Mollusca of the Winton Formation
Taxa Species Presence Material Notes Images
Melanoides[3] Indeterminate
Hyridella[3] H (Protohyridella). goodiwindiensis
H. macmichaeli
Megalovirgus[3] M.wintonensis
Pledgia[3] P. eyrensis

Arthropods

[edit]
Arthropods of the Winton Formation
Taxa Species Presence Material Notes Images
Oribatida?[3] Indeterminate
Odonata[3] Indeterminate
Mecoptera[3] Indeterminate
Coleoptera[3] Indeterminate

Chondrichthyes

[edit]
Chondrichthyes of the Winton Formation
Taxa Species Presence Material Notes Images
Selachii[3] Indeterminate A shark[3]

Dipnoi

[edit]
Dipnoi of the Winton Formation
Taxa Species Presence Material Notes Images
Metaceratodus[4] M. bonei Isolated tooth plates Lungfish belonging to the extinct family Ceratodontidae
M. ellioti
M. wollastoni

Actinopterygii

[edit]
Actinopterygii of the Winton Formation
Taxa Species Presence Material Notes Images
Cladocyclus[5] C. geddesi Nearly complete skull and partial skeleton

Squamates

[edit]
Squamates of the Winton Formation
Taxa Species Presence Material Notes Images
Varanoidea[6] Indeterminate A damaged posterior trunk vertebra Originally considered as dolichosaurid (cf. Coniasaurus),[7] but reassigned

Chelidae

[edit]
Chelidae of the Winton Formation
Taxa Species Presence Material Notes Images
Chelidae[3] Indeterminate

Sauropterygia

[edit]
Sauropterygia of the Winton Formation
Taxa Species Presence Material Notes Images
Plesiosauria[3] Indeterminate

Crocodyliformes

[edit]
Crocodyliformes of the Winton Formation
Taxa Species Presence Material Notes Images
Confractosuchus[8] C. sauroktonos Nearly complete skeleton preserving a juvenile ornithopod in its abdomen
Isisfordia I. duncani Nearly complete skeleton and partial skull, referred complete skull

Dinosaurs

[edit]

Ornithischians

[edit]
Ornithischians of the Winton Formation
Taxa Species Presence Material Notes Images
Amblydactylus A. gethingi Lark Quarry. Multiple footprints.
Ankylosauria[9] Indeterminate Three isolated teeth from left and right dentary and right maxilla
Neornithischia Indeterminate Tooth[10]
Ornithopoda[8] Indeterminate Digested remains associated with the holotype of Confractosuchus[8]
Ornithopoda Undescribed A nearly complete skull and mandible and at least three partial postcranial skeletons.[11] Small-bodied, recovered as part of "Elasmaria"
Wintonopus W. latomorum Snake Creek and Lark Quarry track site. Footprints. An ornithopod.

Sauropods

[edit]
Sauropods of the Winton Formation
Taxa Species Presence Material Notes Images
Australotitan[3] A. cooperensis A partial scapula, humeri, ulna, pubes, ischia, femora, presacral vertebral centrum fragments, and rib fragments. A large diamantinasaurian sauropod that possesses a mosaic of features shared with titanosaurians with similar geographical and temporal range. Possibly a junior synonym of Diamantinasaurus.[12]
Diamantinasaurus[13] D. matildae[13] A squamosal, quadrates, braincase, surangular, atlas intercentrum axis, cervical vertebrae, middle cervical neural arch, co-ossified sacral centra, cervical ribs, dorsal vertebrae, numerous dorsal ribs, fragmentary gastralia, coalesced sacral vertebrae, isolated sacral processes, scapula, coracoid, partial sternal plate, humeri, ulnae, radius, metacarpals I–V, manual phalanges, ilium, pubes, both ischia, femur, tibia, fibula, astragalus, and numerous fragments. A diamantinasaurian sauropod known from partial cranial material.
Savannasaurus[14] S. elliottorum[14] Posterior cervical vertebrae, cervical ribs, dorsal vertebrae, dorsal ribs, sacral vertebrae with processes, partial caudal vertebrae, fragmentary scapula, coracoid, sternal plates, incomplete humeri, shattered ulna, radius, metacarpals I–V, metacarpal IV, manual phalanges, fragments of ilia, pubes, ischia, astragalus, metatarsal III, and associated fragments. A wide-bodied sauropod that was well adapted to the wet, temperate floodplain environment it inhabited.
Sauropoda[8] Indeterminate Poorly preserved remains associated with the holotype of Confractosuchus[8]
Titanosauriformes Undescribed Partial skull, consisting of a braincase, quadrates, quadratojugals, a left squamosal, postorbitals, and several unprepared elements. associated with a hind limb[15]
Wintonotitan[13] W. wattsi[13] A scapula, both humeri, both ulnae, both radii, near complete metacarpus preserving complete metacarpals II–V with proximal half of metacarpal I, fragmentary dorsal and sacral vertebrae and ribs, partial ilium, ischium, caudal vertebral series including anterior caudals, middle caudals, posterior caudals, proximal chevrons, and numerous unidentifiable fragments. A titanosaur that is likely to be closely related to Australotitan, Diamantinasaurus and Savannasaurus.

Theropods

[edit]
Theropods of the Winton Formation
Taxa Species Presence Material Notes Images
Australovenator[13] A. wintonensis Dentaries, dorsal ribs and rib fragments, gastralial ribs and fragments, partial ilium, ulnae, radius, manus metacarpals, unguals, femur, tibiae, fibula, astragalus, metatarsals, pedal phalanges, humeri, radiale, distal carpal, and manual phalanxes. A megaraptoran theropod known from postcranial and cranial material.
Megaraptoridae[16] Indeterminate A partial skeleton, consisting of caudal vertebrae, metatarsals, a phalanx, and numerous unidentifiable fragments. Stated to be larger than Australovenator.

Pterosaurs

[edit]
Pterosaurs of the Winton Formation
Taxa Species Presence Material Notes Images
Ferrodraco[17] F. lentoni A partial premaxillae, maxillae and dentaries, partial frontal, mandibular articular region comprising the surangular, angular and articular, partial cervical vertebrae, partial scapulocoracoid, partial ulna, partial radius, proximal and distal carpals, metacarpal IV, proximal end of metacarpal IV, fragmentary non-wing manual phalanges, partial first wing phalanx (IV-1), and associated fragments. The most complete pterosaur from Australia and the youngest known anhanguerian.

Therapsida

[edit]
Therapsida of the Winton Formation
Taxa Species Presence Material Notes Images
Cynodont[3] Indeterminate


Flora

[edit]
Flora of the Winton Formation[18]
Taxa Species Presence Material Notes Images
Angiospermae Indeterminate Leaf impressions, cuticle fragments At least ten distinct types, belonging to both monocots and dicotyledons
Araucaria A. cf. mesozoica[19] Leaves A member of Araucariaceae
Araucariaceae Indeterminate Leaves Conifer
Austrosequoia A. wintonensis Cones and leaved axes A member of Cupressaceae
Carnoconites[19] Indeterminate Female ovulate fruiting organ A member of the extinct seed plant order Pentoxylales, youngest record of the group in Australia
Cheirolepidiaceae Four taxa Dispersed cuticle Conifer
Emwadea E. microcarpa Seed cones A member of Araucariaceae, more closely related to Agathis and Wollemia than Araucaria.[20]
Equisetites Indeterminate Axes Horsetail
Ginkgo G. wintonensis, four other possible species Leaf impressions (G. wintonensis) Dispersed cuticle A gingophyte, genus extant.
Lovellea L. wintonensis Permineralised flower A member of Laurales
Aff. Lygodium? Indeterminate Fern pinna Fern
Marchantites M. marguerita Liverwort
Microphyllopteris cf. M. gleichenoides Frond fragment impression A fern belonging to the family Gleicheniaceae
Otozamites cf. O. bengalensis Leaves Member of Bennettitales
Phyllopteroides P. macclymontae Numerous pinnule impressions A fern belonging to the family Osmundaceae
Pterostoma Indeterminate Leaves A possible cycad
Ptilophyllum Indeterminate Leaves Member of Bennettitales
Sphenopteris[19] Indeterminate Leaves A "seed fern"
Taeniopteris Indeterminate Leaf impression A member of the extinct seed plant order Pentoxylales, youngest record of the group in Australia
Tempskya T. judithae Permineralized false trunks A tree fern

See also

[edit]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Winton Formation

View on Grokipedia
from Grokipedia
The Winton Formation is a geological formation in the Eromanga Basin of central-western , , extending into parts of northeast and northwest , deposited during the late to early stages approximately 100 to 93 million years ago in a fluvial to lacustrine environment characterized by meandering rivers, floodplains, and seasonal wetlands. Composed primarily of heterogeneous sedimentary rocks including volcanolithic sandstones, mudstones, siltstones, claystones, minor conglomerates, and seams, the formation reaches thicknesses of up to 1,100 , with typical ranges of 400 to 1,000 in the central Eromanga Depression. The depositional setting reflects a warm, humid paleoclimate with annual rainfall exceeding 1,300 mm and multi-year cycles of wet and dry seasons, supporting diverse ecosystems on alluvial plains at a paleolatitude of about 50°S. The Winton Formation is globally significant for its exceptional fossil record, preserving mid- terrestrial vertebrates and plants from the Manuka Subgroup of the Rolling Downs Group, including theropod dinosaurs such as and sauropods like Wintonotitan, alongside crocodyliforms, turtles, lungfish, and early angiosperms. Recent studies (as of 2025) have identified new sauropod specimens and fossilized gut contents, further highlighting its paleobiological importance. Iconic sites like the Lark Quarry Trackways, featuring over 3,000 dinosaur footprints in the upper member, highlight its role in understanding and behavior. Additionally, the formation hosts substantial low-rank resources ( to sub-bituminous) at shallow depths, with low sulfur and ash content, influencing regional resource assessments.

Geology

Location and Extent

The Winton Formation is primarily exposed in the central-western region of , , within the Eromanga Basin, and extends into the northeast of and the northwest of . It forms part of the broader system, with its distribution mapped across these jurisdictions based on surface outcrops and subsurface interpretations. Key outcrop areas are concentrated around the town of Winton (22°23′S 143°02′E), including sites at Elderslie Station, Belmont Station, Lovelle Downs Station, Lark Quarry Conservation Area, and Bladensburg National Park. The formation's surface coverage blankets extensive areas of the Eromanga Basin, with outcrops often limited by overlying or younger strata, resulting in patchy exposures across low-relief plains and hills. Subsurface extent is delineated through data, revealing a regional distribution that aligns with the basin's geometry, where the formation underlies younger sediments over a broad area interpreted at a 1: scale. Thickness varies significantly, reaching up to 1,000 meters or more in depocenters based on drillhole intercepts, though surface expressions are thinner due to post-depositional . In relation to modern topography, the Winton Formation is exposed primarily through erosion and local faulting, which have removed overlying cover and revealed the unit in erosional windows across the arid landscape. This exposure is most prominent in the gently undulating terrain of central-western , where weathering has shaped accessible outcrops for geological study, while subsurface continuity is confirmed by and exploration boreholes.

Stratigraphy

The Winton Formation constitutes the uppermost unit of the Rolling Downs Group within the intracratonic Eromanga Basin of northeastern . It represents a significant non-marine component of the stratigraphic succession in the region, marking a transition from underlying marine deposits to terrestrial sediments. The formation conformably overlies the marine Mackunda Formation across much of its extent, with local variations where it directly overlies the older Allaru Formation due to depositional pinching out of the Mackunda. In areas of exposure or erosion, it is unconformably overlain by or sediments, including those of the . The type section is designated near Winton in central-western , specifically in the vicinity of Elderslie and Lovelle Downs Stations, where the formation's lower and upper divisions are well-exposed. Thickness of the Winton Formation varies regionally, attaining up to approximately 200 meters in eastern portions of the Eromanga Basin and thickening westward to over 1,000 meters in depocenters toward . This lateral variation reflects depositional gradients in the ancient fluvial systems that accumulated the sediments. Stratigraphically, the Winton Formation correlates with equivalent non-marine units in the adjacent Surat Basin to the east, including the Springbok Sandstone and Gubberamunda Sandstone, based on lithostratigraphic and palynological similarities. These correlations highlight the interconnected depositional history across the broader system during the mid-Cretaceous.

Lithology and Depositional Environment

The Winton Formation consists primarily of siliciclastic sedimentary rocks, including fine- to medium-grained volcanolithic s, siltstones, mudstones, and claystones, with minor occurrences of conglomerates and seams. These rocks are characterized by feldspatholithic to lithofeldspathic arenites, often featuring current ripple cross-lamination, trough and tabular cross-stratification, and sandstone concretions formed during early . The presence of minor indicates localized organic-rich accumulation in swampy settings. Sedimentary facies within the formation reflect a range of fluvial and associated environments, including channel sandstones indicative of meandering rivers, overbank mudstones and siltstones from floodplain deposits, and finer-grained lacustrine and mire in minor lakes and swamps. These facies exhibit repetitive sequences with low-energy features such as ripple cross-lamination and probable deposits, suggesting deposition in a low-gradient system with infrequent scouring floods. The depositional model for the Winton Formation involves meandering river systems traversing coastal alluvial plains, which filled the subsiding Eromanga Basin following the regression of the epicontinental Eromanga Sea. This transition from marine to terrestrial conditions is evident in the lowermost units, where fluvial channels and flood basins formed proximal to the retreating seaway, with mixed marine and meteoric influences during early deposition. Paleogeographically, the formation records low-gradient alluvial plains situated proximal to the waning Eromanga Sea in central-western , at approximately 50°S paleolatitude, as part of the broader infilling of the Eromanga Basin during the final stages of . This setting supported a freshwater-dominated landscape with seasonal rainfall and warm temperatures, facilitating the development of extensive riverine and environments. Taphonomic conditions in the Winton Formation favored preservation through rapid burial in and overbank settings, as well as early diagenetic processes in silica-rich, anaerobic environments that led to minimal compression and silicification of remains. concretions, cemented by and formed syndepositionally via sulfate reduction and of , commonly encase and plant fossils with preserved three-dimensional structure.

Age and Geochronology

The Winton Formation spans the late Albian to early stages of the , corresponding to approximately 104–92 million years ago. This temporal framework is established through integrated biostratigraphic, radiometric, and stratigraphic correlations, providing constraints on the deposition of its fluvial and lacustrine sediments. Biostratigraphic evidence primarily derives from palynomorph assemblages, which align the formation with the Coptospora paradoxa Zone (Burger's Assemblage Zone III), indicative of late to early ages. These spore-pollen taxa, including Coptospora paradoxa and Phimopollenites pannosus, dominate preserved organic matter and confirm the formation's position above the late marine Mackunda Formation, which yields ammonites such as Szivesites sp. diagnostic of that stage. No or younger marine index fossils occur within the Winton Formation itself, supporting its nonmarine character and . Radiometric dating via U-Pb analysis of detrital zircons from volcaniclastic sandstones provides maximum depositional ages, with the youngest concordant grains clustering around 100.5–103 Ma (latest ) for lower sections and as young as 92.5–93.9 Ma (earliest ) in upper, fossil-rich horizons. These results, derived from inductively coupled plasma mass spectrometry (LA-ICP-MS) on over 300 grains across multiple sites, indicate initial sedimentation no earlier than ~103 Ma and ongoing deposition through the Cenomanian-Turonian boundary. Magnetostratigraphic correlation is limited by the Normal Superchron (quiet magnetic zone spanning ~120–83 Ma), rendering polarity reversals unavailable for fine-scale resolution; instead, global stage correlations rely on the aforementioned and radiometric data. Post-2013 studies have refined these constraints through additional detrital analyses, confirming maximum ages of 100.5–102.2 Ma for lower sections at sites like Isisford and extending the upper range to lowermost (~92 Ma) based on integrated provenance and stratigraphic modeling. These updates enhance correlations with contemporaneous Gondwanan units, such as the Griman Creek Formation in eastern .

History of Research

Naming and Early Studies

The Winton Formation was formally named in 1955 by Frederick William Whitehouse, who designated its type section based on borehole data from water and exploration wells in and around the town of . Whitehouse described the unit as comprising blue shales, sandstones, and intercalated coal seams, representing fluvial and lacustrine deposits that form the uppermost part of the Rolling Downs Group in the Eromanga Basin. This naming refined earlier informal references to the sediments and emphasized their distinction from underlying marine units, drawing on both subsurface cores and limited surface outcrops across central-western . Prior to Whitehouse's work, the rocks now assigned to the Winton Formation had been noted in early 20th-century regional geological surveys as part of broader sequences. In 1916, Benjamin Dunstan referred to them as the "Winton Series," describing interbedded sandstones, shales, mudstones, and coal measures overlying marine strata in the Winton district. These early accounts, based on surface observations and initial well logs, placed the series within the non-marine upper of the Eromanga Basin, though without precise boundaries or type sections. Initial stratigraphic assignments often conflated the Winton Formation with adjacent units, particularly the conformably underlying Mackunda Formation, due to their transitional depositional environments from shallow marine to fluvial settings. Before 1955, both were commonly grouped under terms like "Rolling Downs Shales" in regional mappings, leading to ambiguities in correlations across the basin. Whitehouse's 1955 definitions resolved much of this confusion by using borehole and fossil content to delineate the contact, with the Mackunda characterized by glauconitic sands and the Winton by coarser, coal-bearing clastics. First paleontological notes on bones in the strata of the Eromanga Basin region were reported in the late 19th and early 20th centuries by pastoralists and explorers, who encountered large fossilized remains during land management activities on stations near Winton and Richmond. These informal reports, including fragments sent to museums, highlighted the potential for vertebrate fossils in the non-marine units and preceded formal descriptions such as that of Austrosaurus mckillopi from nearby strata in 1933.

Major Discoveries and Fossil Sites

One of the most iconic fossil sites in the Winton Formation is the Dinosaur Stampede National Monument at Lark Quarry Conservation Park, located about 110 km southwest of Winton in central-western . Discovered in 1976 by local pastoral workers, the site preserves approximately 3,300 individual theropod dinosaur footprints in a single sandstone layer, dated to around 95 million years ago. This trackway assemblage, covering an area of about 120 square meters, was originally interpreted as recording a "stampede" event with small- to medium-sized theropods pursuing larger ornithopod prey, providing evidence of predatory behavior in the ; however, subsequent studies (as of 2013) suggest the tracks may represent multiple individuals traversing the site over time, possibly including swim tracks, rather than a single event. The site's significance led to its designation as a in 2004, with ongoing conservation efforts by Queensland's Department of Environment and Science. In the Richmond and Winton districts, extensive bone beds have yielded significant sauropod remains, highlighting the formation's role as a key repository for titanosaur fossils. A notable example is the partial skeleton of Australotitan cooperensis, dubbed the "Eromanga Titan," excavated from a site near Eromanga starting in 2007 by the Eromanga Natural History Museum. This specimen, comprising vertebrae, limb bones, and other elements, represents one of Australia's largest known dinosaurs and was formally described in 2021 based on material recovered over more than a decade of fieldwork. These bone beds, often exposed in outcrops along river systems, have produced multiple associated skeletons, underscoring the depositional environment's favorability for preserving large vertebrate remains. The Australian Age of Dinosaurs Museum, established near Winton, has been central to ongoing excavations since , when operations relocated to a dedicated 1,400-hectare site at The Jump-Up donated by local landowners. Annual digs, involving museum staff, volunteers, and collaborations with institutions like the Queensland Museum, have uncovered numerous dinosaur specimens from the Winton Formation, including partial skeletons of sauropods and theropods such as those contributing to the descriptions of Diamantinasaurus matildae and . By 2010, these efforts had yielded over 20 major fossil sites on nearby properties like Elderslie and Belmont Stations, with preparations ongoing for hundreds of bone fragments in the museum's laboratory. This systematic program has significantly expanded the known vertebrate diversity from the region. More recent discoveries (2020–2025) include fragmentary megaraptorid theropod remains near the type locality of Australovenator wintonensis (described 2020), additional sauropod specimens re-evaluated in comprehensive studies (2021), and the Snake Creek Tracksite, a diverse vertebrate ichnoassemblage preserving the first sauropod tracks from the formation (reported 2021). These finds continue to enhance understanding of the Winton Formation's faunal diversity through ongoing museum and academic collaborations. Early 20th-century collections laid the groundwork for Winton Formation , with museums like the Museum acquiring initial specimens through regional surveys. For instance, the of Austrosaurus mckillopi, consisting of seven dorsal vertebrae and other elements, was discovered in 1932 on Clutha Station near Richmond by station overseer Henry Burgoyne Wade and described the following year. Later mid-century finds, such as the partial sauropod skeleton later named Wintonotitan wattsi recovered near Winton in the 1970s, further enriched institutional collections and prompted renewed interest in the formation's potential. These historical efforts, often opportunistic during pastoral activities, established the area's reputation as a hotspot. Expeditions in the , including surveys tied to resource exploration in the Eromanga Basin, have revealed additional non-dinosaurian fossils, such as crocodyliform remains from Elderslie Station excavated in 2010 and bones from Belmont Station found in 2017. The crocodyliform specimen, including a partial and postcranial elements, represents a primitive eusuchian and was recovered during targeted paleontological assessments. The material, comprising wing elements of the anhanguerid Ferrodraco lentoni, marks the first such discovery in the Winton Formation and was unearthed by grazier Bob Elliott, leading to formal description in 2019. These finds, often from private land holdings, have broadened understanding of the formation's aquatic and aerial faunas through collaborative academic and museum-led initiatives.

Paleontology

Flora

The flora of the Winton Formation is characterized by a diverse assemblage of vascular plants, reflecting a transitional phase in Australian vegetation from gymnosperm-dominated ecosystems to those with increasing angiosperm influence. Dominant groups include early angiosperms, such as and podocarps, ferns, bennettitaleans (cycad-like plants), and ginkgophytes, with angiosperms and co-dominating the assemblage. Over 50 macrofossil plant taxa have been identified, underscoring high diversity in this mid- setting. Key taxa are represented primarily by leaf impressions and fragmentary reproductive structures. Angiosperms are evidenced by simple to lobed dicotyledonous leaves, including forms suggestive of early laurel-like or hamamelid affinities. Conifers include Araucaria-like foliage and shoots, as well as podocarp woods assigned to Protophyllocladoxylon wintonense, indicating a significant podocarp component supported by palynological data. Bennettitales are present through fronds such as Otozamites and Ptilophyllum, while ferns like Cladophlebis and Phyllopteroides occur sporadically, and ginkgophytes are represented by Ginkgoites leaves. Cycad-like elements are noted but less abundant. Plant fossils are predominantly preserved as compressions and impressions in fine-grained siltstones, mudstones, and thin seams, derived from swampy, low-energy depositional settings such as floodplains and channel margins. These preservation modes capture delicate venation and cuticular details, though permineralized woods and rare cones provide additional anatomical insights. Paleoecologically, the Winton suggests a humid subtropical environment with riparian along meandering rivers, where angiosperms were radiating and occupying mid- to upper-canopy niches alongside . This assemblage indicates seasonally wet conditions supporting diverse elements like ferns and bennettitaleans, marking a key stage in the angiosperm diversification across .

Invertebrate Fauna

The invertebrate fauna of the Winton Formation is notably sparse relative to the abundant vertebrate remains, yet it includes key molluscan and fossils that illuminate the mid-Cretaceous fluvial and lacustrine paleoenvironments of central-western . These fossils, primarily body impressions and rare trace structures, occur in fine-grained siltstones and mudstones, preserving evidence of both aquatic and terrestrial habitats. Molluscan remains dominate the known invertebrate record, consisting mainly of freshwater bivalves adapted to slow-flowing rivers and associated with lacustrine deposits. At least two types of small bivalves or mussels have been identified, including the species Prohyria macrimichaeli, whose presence supports interpretations of low-energy fluvial settings. Gastropods are exceptionally rare, with only two poorly preserved freshwater specimens documented as the first such records from the formation, highlighting their limited occurrence in these continental sediments. Arthropod fossils, particularly from Insecta, are represented by isolated impressions of wing cases, wings, wing fragments, and cicadids, often found in association with sauropod bonebeds in layers. Trace fossils further indicate arthropod activity, including crayfish-like burrows (Camborygma ichnospecies) that suggest burrowing behavior by decapod crustaceans in marginal aquatic zones. Overall, the low diversity of these —contrasting sharply with the richer assemblage—emphasizes their role as environmental indicators, particularly signaling persistent freshwater conditions amid a warm, humid continental landscape.

Fish Fauna

The fauna of the Winton Formation, primarily preserved in fluvial and deposits, consists mainly of disarticulated teeth, scales, and partial skeletons indicative of freshwater environments with seasonal variations. These assemblages reflect to riverine and lacustrine systems, where dominated and predatory ray-finned fishes occupied higher trophic levels. Chondrichthyes are represented by indeterminate teeth, suggesting the presence of freshwater-adapted elasmobranchs in the formation's deltaic and riverine settings. These remains, often fragmented and associated with sediments, indicate as occasional inhabitants of the aquatic ecosystems, though no formal species have been described from the unit. Dipnoans, particularly ceratodontid , form a significant component of the , with three species documented: sp., Metaceratodus ellioti, and Metaceratodus wollastoni. These taxa, known from isolated plates and dentaries, exhibit endemic and adaptations such as robust for crushing, suited to the seasonal of rivers and lakes in the mid-Cretaceous landscape. remains are abundant in overbank deposits, underscoring their ecological dominance in low-oxygen, variable aquatic habitats. Actinopterygians include primitive ray-finned forms, with notable records of an elopomorph resembling modern tarpons (Megalops) and the ichthyodectiform Cladocyclus gardneri. The elopomorph, represented by a partial exceeding 1 meter in length from near Isisford, features a predatory morphology adapted to fast-flowing rivers. Cladocyclus gardneri, based on an articulated skull and anterior body (QM F44329) from upper strata near Isisford, measures 0.6–1.05 meters and marks the first eastern Gondwanan occurrence of this genus, highlighting its freshwater incursions. A possible halecomorph is also reported from Isisford, though its affinities remain unconfirmed pending further study. These ray-finned fishes, preserved as disarticulated elements in volcaniclastic sandstones, played key roles as predators in the formation's river systems.

Non-Dinosaurian Reptiles

The non-dinosaurian reptiles of the Winton Formation represent a modest but significant component of the mid-Cretaceous assemblage, primarily comprising semi-aquatic forms adapted to the fluvial and deltaic environments of eastern . These taxa, including squamates, , and , are preserved as isolated elements or partial skeletons within concretions and claystones, often indicating in low-energy channel sands or overbank deposits associated with riverine systems. Their diversity, estimated at around 5–10 taxa based on body fossils and tracks, underscores the formation's role as a mosaic of freshwater and brackish habitats proximal to the Eromanga Sea. Squamates are sparsely represented, with the most notable find being a single posterior trunk (QM F52673) identified as a dolichosaurid , cf. Coniasaurus. This procoelous , measuring approximately 1.5 times longer than wide and exhibiting varanoid features without pachyostosis, marks the earliest or second-earliest record of a squamate in and the first from non-marine Gondwanan deposits. Recovered from silty claystone in the lower (latest ) portion of the formation via wet sieving, it suggests adaptation of marine dolichosaurids to freshwater settings, possibly facilitated by warming sea-surface temperatures and oceanic connectivity during the mid-Cretaceous. Indeterminate skink-like remains further hint at terrestrial or semi-aquatic diversity, though these are fragmentary and lack formal . Turtles (Testudines) are primarily chelids, reflecting the dominance of freshwater pleurodires in Australian ecosystems. Identifiable remains consist of fragments and internal molds from multiple sites, including the Matilda Site (AODL 85), preserved in fine-grained clays indicative of lakes or low-energy fluvial settings. These chelids, potentially akin to basal forms like Chelodina, exhibit flattened, oval suited to riverine , with no named yet erected from the formation. A rare chelonioid cast (QM F12413) from the lowermost section, featuring reduced costal plates and fontanelles, suggests occasional marine incursions into tidal-fluvial zones, though its nature remains debated. Crocodyliformes dominate the reptile record, with at least two named eusuchian genera highlighting semi-aquatic predation in delta-plain habitats. Isisfordia duncani, a basal eusuchian reaching 1.1 m in length, is known from multiple specimens including a near-complete articulated holotype (QM F36211) and partial skeletons (e.g., QM F34642, QM F44319), preserved in calcite-cemented sandstone concretions with minimal abrasion, denoting autochthonous burial by floodwaters. These fossils, from the upper Albian near Isisford, include juveniles and adults, implying brackish-water tolerance and thermoregulation in standing pools. Confractosuchus sauroktonos, a larger macro-generalist (2–2.5 m), is represented by a near-complete skull and semi-articulated postcrania (AODF 0890) from Cenomanian strata, containing gastric residues of a juvenile ornithopod dinosaur, evidencing ambush predation and dismemberment capabilities. Both genera's partial skeletons in channel sands reflect lifestyles tied to distributary channels and overbanks. Sauropterygia are rare, with marine-influenced occurrences limited to proximal fluvial areas. An elasmosaur specimen discovered in 2022 from Elderslie Station, comprising a partial and , represents one of Australia's most complete such finds from the formation (~100 Ma), suggesting occasional upstream migration into riverine systems. These fragmentary remains align with the semi-aquatic theme, preserved in sediments transitional to marine influences.

Dinosaurs

The dinosaurian fauna of the Winton Formation is characterized by a predominance of sauropodomorphs, with theropods and ornithischians represented by more fragmentary remains. Fossils primarily consist of partial skeletons, isolated bones, and teeth, reflecting a fluvial that favored the preservation of large-bodied herbivores alongside opportunistic predators. This assemblage provides key insights into mid-Cretaceous in eastern , highlighting a structured around abundant supporting multiple titanosauriform lineages. Ornithischian remains are exceedingly rare in the Winton Formation, with no complete specimens documented. Fragmentary osteoderms and possible limb elements suggest the presence of ankylosaurians, representing the first evidence of thyreophorans in this unit and indicating a minor role for armored herbivores in the ecosystem. Referrals of material to the ornithopod have been proposed based on isolated postcranial elements but remain debated due to stratigraphic and morphological uncertainties, as the genus is primarily known from underlying formations. Sauropods dominate the known dinosaur diversity, all belonging to the Titanosauriformes and comprising medium- to large-bodied quadrupedal adapted to the formation's settings. matildae, described from a partial including fore- and hindlimbs, , and vertebrae, exemplifies a robust diamantinasaurian titanosaur with a body length estimated at 12–15 meters. In 2025, fossilized gut contents preserved within a specimen of matildae provided the first direct evidence of sauropod herbivory, revealing a diet of diverse plant material from low- to high-level with minimal . Wintonotitan wattsi, known from a partial , dorsal vertebrae, and limb elements, represents a more slender wintonotitanin with an estimated length of 10–13 meters, distinguished by its elongated cervicals. Savannasaurus elliottorum, based on an incomplete preserving much of the axial and , features notably wide hips (over 1.1 meters across) and a body length of about 15 meters, showcasing plesiomorphic titanosaur traits alongside derived pelvic adaptations for enhanced stability. In 2021, Australotitan cooperensis was named from large limb bones (including a 1.7-meter-long ), suggesting a gigantic titanosaur up to 30 meters long and weighing 70 tons, the largest known from ; however, ongoing analyses question its distinctiveness, proposing potential synonymy with based on proportional similarities and phylogenetic placement. At least four valid sauropod taxa are recognized, with additional unnamed specimens indicating further diversity within this . Theropod remains are less common but include significant carnivorous forms, primarily megaraptorans that likely preyed on juvenile or subadult sauropods. Australovenator wintonensis, the best-known theropod from the formation, is represented by a partial including the hindlimbs, , and partial forelimbs, revealing a bipedal predator about 5–6 meters long with hypertrophied manual claws suited for grasping; initially classified as a carcharodontosaurid, it is now firmly placed within Megaraptoridae based on updated phylogenetic analyses. Isolated teeth and postcranial fragments hint at possible spinosaurid presence, though these await formal description and confirmation. Trackways, such as those at the Lark Quarry Dinosaur site, preserve tridactyl impressions attributed to theropods, depicting a group of small- to medium-sized individuals in a preserved "stampede" event interpreted as defensive against a larger predator. Overall, the Winton Formation yields at least 6–8 taxa, underscoring a sauropod-dominated community supplemented by diverse but low-abundance carnivores, consistent with a productive . Recent 3D efforts have refined understandings of ontogenetic variation and taxonomic boundaries among sauropods, enhancing reconstructions of this Gondwanan fauna.

Mammaliaforms

Mammaliaforms, the encompassing mammals and their closest extinct relatives, are currently unknown from the Winton Formation, despite the unit's rich record of other terrestrial vertebrates such as and crocodyliforms. Extensive surveys and excavations in the formation's fine-grained sediments, which preserve isolated teeth and small bones of other taxa, have not recovered any synapsid remains, including jaw fragments or dental elements typical of indeterminate mammaliaforms. This absence contrasts with the low-diversity but documented mammaliaform records elsewhere in , primarily from deposits in southern states, where australosphenids and haramyid-like multituberculates indicate insectivorous habits and Gondwanan affinities. The lack of mammaliaform fossils in the Winton Formation underscores a broader gap in mid-Cretaceous mammalian for northern , with no evidence of therapsid-grade or more derived forms like cynodonts reclassified post-2000 studies. Preservation biases toward larger diapsids may contribute, as fine sediments at sites like Isisford and Richmond yield small aquatic taxa but few terrestrial micromammals. If present, any mammaliaforms would represent the earliest evidence for , potentially filling biogeographic voids between southern australosphenids and marsupials.

References

  1. https://www.bioregionalassessments.gov.au/assessments/12-resource-assessment-galilee-subregion/12115-winton-formation
  2. https://pmc.ncbi.nlm.nih.gov/articles/PMC6130253/
  3. https://www.sciencedirect.com/science/article/abs/pii/S0037073817301240
  4. https://peerj.com/articles/17180/
  5. https://www.discoverwildlife.com/dinosaurs/diamantinasaurus-matildae-fossilised-gut-australia
  6. https://ecat.ga.gov.au/geonetwork/srv/eng/catalog.search#/metadata/fc3eec81-5e4f-6f5c-e044-00144fdd4fa6
  7. https://latitude.to/articles-by-country/au/australia/20774/winton-queensland
  8. https://dinosaurs.group.uq.edu.au/winton-formation
  9. https://researchonline.jcu.edu.au/34439/1/JCU_34439-tucker-2014-thesis.pdf
  10. https://doi.org/10.7717/peerj.5513
  11. https://doi.org/10.2110/jsr.2016.67
  12. https://doi.org/10.1016/j.sedgeo.2017.05.004
  13. https://royalsocietypublishing.org/doi/10.1098/rsos.220381
  14. https://www.sciencedirect.com/science/article/abs/pii/S1342937X12004157
  15. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0006190
  16. https://peerj.com/articles/5513/
  17. https://www.researchgate.net/publication/235350644_Detrital_zircon_age_constraints_for_the_Winton_Formation_Queensland_Contextualizing_Australia%27s_Late_Cretaceous_dinosaur_faunas
  18. https://pubs.geoscienceworld.org/sepm/jsedres/article/86/9/1067/321192/Depositional-Environment-of-the-Lower-Cretaceous
  19. https://www.sciencedirect.com/science/article/abs/pii/S0031018218305960
  20. http://jurassic.ru/pdf/moore_pitt1985_cretaceous_eromanga.pdf
  21. https://demstedpprodaue12.blob.core.windows.net/mesac-public/resources/files/4355986/RB9000055.pdf
  22. https://dinosaurs.group.uq.edu.au/files/2107/Romilio_et_al_2013.pdf
  23. https://www.researchgate.net/publication/277362129_Vertebrate_Palaeontology_in_Queensland
  24. https://media.australian.museum/media/dd/Uploads/Documents/38138/ams370_vXIX_09_lowres.5ec9b66.pdf
  25. https://pmc.ncbi.nlm.nih.gov/articles/PMC8216175/
  26. https://pmc.ncbi.nlm.nih.gov/articles/PMC8191491/
  27. https://www.scimex.org/newsfeed/meet-australias-largest-dinosaur-australotitan%2C-the-southern-titan
  28. https://www.australianageofdinosaurs.com/page/54/australian-age-of-dinosaurs-our-history
  29. https://openresearch.newcastle.edu.au/ndownloader/files/54416348
  30. https://royalsocietypublishing.org/doi/10.1098/rsos.191462
  31. https://www.australianageofdinosaurs.com/page/119/australian-age-of-dinosaurs-new-discoveries
  32. https://australian.museum/learn/dinosaurs/fact-sheets/wintonotitan-wattsi/
  33. https://www.nature.com/articles/s41598-019-49789-4
  34. https://doi.org/10.1080/03115511003669944
  35. https://espace.library.uq.edu.au/view/UQ:335413
  36. https://pubs.geoscienceworld.org/sepm/palaios/article/29/3/121/146380/PALEOCLIMATE-OF-THE-LATE-CRETACEOUS-CENOMANIAN
  37. https://dinosaurs.group.uq.edu.au/other-winton-formation-fossils
  38. https://search.informit.org/doi/10.3316/informit.T2025070700000900229300307
  39. https://peerj.com/articles/10640/
  40. https://www.app.pan.pl/archive/published/app59/app20120019.pdf
  41. https://austhrutime.com/winton_formation.htm
  42. https://www.tandfonline.com/doi/abs/10.1080/03115518.2019.1701078
  43. https://www.jstor.org/stable/4523782
  44. https://peerj.com/articles/11544/
  45. https://news.uq.edu.au/article/2010/07/large-predatory-fish-fossil-found-near-isisford
  46. https://royalsocietypublishing.org/doi/10.1098/rsos.171651
  47. https://www.sciencedirect.com/science/article/pii/S1342937X22000338
  48. https://www.researchgate.net/publication/265164190_A_dolichosaurid_lizard_from_the_latest_Albian_mid-Cretaceous_Winton_Formation_Queensland_Australia
  49. https://museumsvictoria.com.au/media/4238/017-028_mmv74_kear_2_web.pdf
  50. https://www.theguardian.com/science/2022/dec/06/queensland-graziers-unearth-100m-year-old-plesiosaur-remains-likened-to-rosetta-stone
  51. https://www.cell.com/current-biology/fulltext/S0960-9822(25)00550-0
  52. https://doi.org/10.7717/peerj.17180
  53. https://royalsocietypublishing.org/doi/10.1098/rsos.221618
  54. https://www.researchgate.net/publication/242298287_Chapter_3_Diversity_of_Early_Cretaceous_Mammals_from_Victoria_Australia
  55. https://www.researchgate.net/publication/40662906_An_enigmatic_Synapsid_tooth_from_the_Early_Cretaceous_of_New_South_Wales_Australia
  56. https://depositsmag.com/2017/12/05/australias-polar-cretaceous-mammals/
Add your contribution
Related Hubs
User Avatar
No comments yet.