''Asfaltovenator'' (meaning "Cañadón Asfalto Formation hunter" after the fossil formation in which its fossils were found) is a genus of possibly allosauroid

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

from the Lower Jurassic (Middle

Toarcian The Toarcian is, in the International Commission on Stratigraphy, ICS' geologic timescale, an age (geology), age and stage (stratigraphy), stage in the Early Jurassic, Early or Lower Jurassic. It spans the time between 184.2 Megaannum, Ma (million ...

) Cañadón Asfalto Formation of

Chubut Province Chubut ( from Tehuelche language, Tehuelche 'transparent'; ) is a provinces of Argentina, province in southern Argentina, situated between the 42nd parallel south (the border with Río Negro Province), the 46th parallel south (bordering Santa ...

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

. The

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...

and only species is ''Asfaltovenator vialidadi''.

Discovery

In 2002, technician Leandro Canesa discovered a theropod skeleton roughly a

mile The mile, sometimes the international mile or statute mile to distinguish it from other miles, is a imperial unit, British imperial unit and United States customary unit of length; both are based on the older English unit of Unit of length, le ...

north of Cerro Condor. Excavations started in 2005, and the fossil was removed in its entirety in 2007. It was then prepared by Mariano Caffa, a process that took five years due to the extreme hardness of the stone matrix. Between 2013 and 2015, it was compared with the specimens of related theropods. In 2019, the type species ''Asfaltovenator vialidadi'' was named and described by Oliver Walter Mischa Rauhut and Diego Pol. The generic name combines a reference to the Cañadón Asfalto Formation with the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word ''venator'', meaning "hunter". The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

honours the Dirección Nacional de Vialidad for assisting the Museo Paleontológico "Egidio Feruglio" in recovering the fossil. ''Asfaltovenator'' is only known from the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

specimen MPEF PV 3440, which was found in a layer of the Cañadón Asfalto Formation which dates to the Middle

(179-178 million years old). The age was established by using zircon datation, with the location of the specimen being closer to the younger date. The holotype consists of a partial skeleton with a skull, and includes the mostly complete skull and lower jaws and most of the postcranial skeleton in front of the hips, including ten cervical (neck) vertebrae, thirteen dorsal (back) vertebrae and the first sacral vertebra, the complete shoulder girdle minus the furcula, and both forelimbs. The holotype also includes the distal portion of the

pubic bones In vertebrates, the pubis or pubic bone () forms the lower and anterior part of each side of the hip bone. The pubis is the most forward-facing (ventral and anterior) of the three bones that make up the hip bone. The left and right pubic bones ar ...

as well as a partial right hindlimb consisting of the distal portion of the femur and proximal portions of the tibia and fibula, and a partial foot.

Description

''Asfaltovenator'' was a fairly large animal similar in size to ''Allosaurus'', with the holotype skull being in length and the total body length being estimated at . The describers identified several distinctive features, some of which are autapomorphies, seen on the premaxillary teeth serrations and foramen (albeit shared with more basal neotheropods like ''

Dilophosaurus ''Dilophosaurus'' ( ) is a genus of theropod dinosaurs that lived in what is now North America during the Early Jurassic, about 186 million years ago. Three skeletons were discovered in northern Arizona in 1940, and the two best preserv ...

'', '' Dracovenator'', and the coelurosaur '' Proceratosaurus''), and on the paradental plates and palatal shelf (also shared with ceratosaurians & others). In the other side it has clear allosauroid features, including on the premaxilla (also recorded in some megalosauroids), the maxilla, or the lacrimal with a supraantorbital crest. The exoccipital bone of the rear skull shows distinctive horizontal ridges between the paraoccipital process and the

foramen magnum The foramen magnum () is a large, oval-shaped opening in the occipital bone of the skull. It is one of the several oval or circular openings (foramina) in the base of the skull. The spinal cord, an extension of the medulla oblongata, passes thro ...

. On the third and fourth neck vertebrae, the neural spines are triangular and swept backwards. The eleventh and twelfth back vertebrae possess an additional forward ridge on the underside of the diapophysis, the process for the articulation facet of the top rib head.

Classification

Due to ''Asfaltovenator'' possessing both primitive and derived characters within Tetanurae, its inclusion in the phylogenetic analysis disrupted current views of tetanuran phylogeny, with the analysis recovering ''Asfaltovenator'' as a basal allosauroid between piatnitzkysaurids and metriacanthosaurids, and traditional Megalosauroidea as a

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

grade leading to

Allosauroidea Carnosauria is an extinct group of carnivorous theropod dinosaurs that lived during the Jurassic and Cretaceous periods. While Carnosauria was historically considered largely synonymous with Allosauroidea, some recent studies have revived Carn ...

. The unique combination of characteristics seen in ''Asfaltovenator'' may also indicate that megalosauroids and allosauroids shared a common ancestor not shared with coelurosaurs, another tetanuran group. Asfaltovenator skull bones and vertebrae

Asfaltovenator skull bones and vertebrae

In 2024, Andrea Cau suggested a different position within Megalosauroidea, as a sister taxon of '' Sciurumimus'' and/or within a larger stem group. In the same year, a study by Oliver Rauhut and colleagues included ''Asfaltovenator'' within

Allosauridae Allosauridae is an extinct family of medium to large bipedal, carnivorous allosauroid theropod dinosaurs from the Late Jurassic. Allosauridae is a fairly old taxonomic group, having been first named by the American paleontologist Othniel Cha ...

based on their phylogenetic analysis. The ongoing osteology notified also this position, also recovering it in a clade with ''

Allosaurus ''Allosaurus'' ( ) is an extinct genus of theropod dinosaur that lived 155 to 145 million years ago during the Late Jurassic period ( Kimmeridgian to late Tithonian ages). The first fossil remains that could definitively be ascribed to th ...

'' in some trees or as an early branching allosauroid of some kind. A monophyletic Carnosauria is not recovered, and the other Cañadón Asfalto tetanurans are not closely related to ''Asfaltovenator''. In 2025, the description of '' Tameryraptor'' also found ''Asfaltovenator'' in Allosauridae in some of their phylogenetic analyses, but this depended on the phylogenetic protocol used.

Paleoecology

The holotype of ''Asfaltovenator'' comes from the Chacritas Member of the Cañadón Asfalto Formation. This member is mostly made up of two major depositional settings: lacustrine and fluvial deposits. Both of these have intervals of tuffaceous materials, suggesting the presence of volcanic activity. Palustrine littoral environment levels are seen at Cerro Cóndor and Estancia Fossati, characterized by the presence of lacustrine limestones interbedded with shales, tuffs and sandstones. The lacustrine section has been called the "Chacritas Paleolake", and seems to have been a rather saline or even hypersaline hydrologically closed pan lake, shallow in depth, with marginal zones and palustrine subenvironments made of low-energy ramp-like margins. The

Toarcian Oceanic Anoxic Event The Toarcian extinction event, also called the Pliensbachian-Toarcian extinction event, the Early Toarcian mass extinction, the Early Toarcian palaeoenvironmental crisis, or the Jenkyns Event, was an extinction event that occurred during the early ...

(TOAE), recently been recognized as a key driver of Jurassic dinosaur evolution, linked to volcanic eruptions in the Karoo-Ferrar region that caused multiple extinction pulses. While well-studied in marine invertebrates, the event's impact on terrestrial vertebrates, particularly tetanuran theropods, is less understood. However, evidence suggests the TOAE triggered rapid diversification in these groups as seen with the presence of ''Asfaltovenator'' and other Averostrans in Middle Toarcian strata. This surge in morphological evolution, followed by a decline in the Middle Jurassic, aligns with patterns seen after other extinction events. Ecological release after the TOAE likely facilitated this rapid evolution, though reconstructing lineage relationships is challenging due to high homoplasy and incomplete fossil records.

References

{{Taxonbar, from=Q78185607 Carnosauria Dinosaur genera Toarcian dinosaurs Cañadón Asfalto Formation Dinosaurs of Argentina Fossil taxa described in 2019