Herrerasauridae is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly mu ...

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 ...

s, possibly basal to either theropods or even all of

saurischia Saurischia ( , meaning "reptile-hipped" from the Greek ' () meaning 'lizard' and ' () meaning 'hip joint') is one of the two basic divisions of dinosaurs (the other being Ornithischia), classified by their hip structure. Saurischia and Ornithi ...

ns, or even their own branching from Dracohors, separate from Dinosauria altogether. They are among the oldest known dinosaurs, first appearing in the fossil record around 233.23 million years ago (the

Carnian The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227.3 ...

stage of the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch a ...

), before becoming extinct by the end of the

stage. Herrerasaurids were relatively small-sized dinosaurs, normally no more than long, although the holotype specimen of "''Frenguellisaurus ischigualastensis"'' (nowadays considered a synonym of ''Herrerasaurus'' ''ischigualastensis'') is thought to have reached around 6 meters (20 ft) long. The best known representatives of this group are from

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

(

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

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 ...

), where they were first discovered in the 1930s in relation to ''Staurikosaurus'' and 1960s in relation to ''Herrerasaurus''. A nearly complete skeleton of '' Herrerasaurus ischigualastensis'' was discovered in the Ischigualasto Formation in

San Juan San Juan, Spanish for Saint John (disambiguation), Saint John, most commonly refers to: * San Juan, Puerto Rico * San Juan, Argentina * San Juan, Metro Manila, a highly urbanized city in the Philippines San Juan may also refer to: Places Arge ...

, Argentina, in 1988. Less complete possible herrerasaurids have been found in

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

and

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

, and they may have inhabited other continents as well. Herrerasaurid anatomy is unusual and specialized, and they are not considered to be ancestral to any later dinosaur group. They only superficially resemble theropods and often present a mixture of very primitive and derived traits. The

acetabulum The acetabulum (; : acetabula), also called the cotyloid cavity, is a wikt:concave, concave surface of the pelvis. The femur head, head of the femur meets with the pelvis at the acetabulum, forming the Hip#Articulation, hip joint. Structure The ...

is only partly open, and there are only two sacral vertebrae, the lowest number among dinosaurs. The

pubic bone 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 ...

has a derived structure, being rotated somewhat posteriorly and folded to create a superficially tetanuran-like terminal expansion, especially prominent in ''H. ischigulastensis''. The hand is primitive in having five

metacarpal In human anatomy, the metacarpal bones or metacarpus, also known as the "palm bones", are the appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones ( wrist bones), which articulate ...

s and the third finger longer than the second, but resembles those of theropods in having only three long fingers, with curved claws. Herrerasaurids also have a hinged

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

, which is also found in theropods.

Classification

It is not clear where herrerasaurids lie on the early dinosaur evolutionary tree. They are possibly basal theropods or basal saurischians. Early researchers even proposed that they represented an early lineage of

sauropodomorph Sauropodomorpha ( ; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had lo ...

s. Some analyses, such as Nesbitt ''et al.'' 2009, have found ''Herrerasaurus'' and its relatives in Herrerasauridae to be very basal theropods, while others (such as Ezcurra 2010) have found them to be basal to the clade Eusaurischia, that is, closer to the base of the saurischian tree than either theropods or sauropodomorphs, but not true members of either. The situation is further complicated by uncertainties in correlating the ages of late Triassic beds bearing land animals. Other proposed members of the

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

have included '' Sanjuansaurus'' from the Ischigualasto Formation of Argentina, '' Staurikosaurus'' and '' Gnathovorax'' from the Santa Maria Formation of southern Brazil, ''

Chindesaurus ''Chindesaurus'' ( ) is an extinct genus of basal saurischian dinosaur from the Late Triassic (213-210 million years ago) of the southwestern United States. It is known from a single species, ''C. bryansmalli'', based on a partial skeleton recov ...

'' from the Petrified Forest ( Chinle Formation) of

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

, and possibly '' Caseosaurus'' from the Dockum Formation of

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

, although the relationships of the North American animals are not fully understood, and not all paleontologists agree. Grzegorz Niedźwiedzki, Stephen L. Brusatte ''et al.'' (2014) described a

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

an putative member of the group on the basis of

Norian The Norian is a division of the Triassic geological period, Period. It has the rank of an age (geology), age (geochronology) or stage (stratigraphy), stage (chronostratigraphy). It lasted from ~227.3 to Mya (unit), million years ago. It was prec ...

age fossils discovered in

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...

. An unnamed herrerasaurid was reported from the Carnian Pebbly Arkose Formation in

Zimbabwe file:Zimbabwe, relief map.jpg, upright=1.22, Zimbabwe, relief map Zimbabwe, officially the Republic of Zimbabwe, is a landlocked country in Southeast Africa, between the Zambezi and Limpopo Rivers, bordered by South Africa to the south, Bots ...

by Griffin ''et al.'' (2022). Other possible basal saurischians include '' Alwalkeria'' from the Late Triassic Maleri Formation of southern

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

, and '' Teyuwasu'' (recently considered synonym of '' Staurikosaurus''), known from very fragmentary remains from the Late Triassic of Brazil. The discovery of the Herrerasaurid '' Gnathovorax'' indicates that the family falls outside the

Theropoda Theropoda (; from ancient Greek iktionary:θηρίον, , (''therion'') "wild beast"; wiktionary:πούς, , wiktionary:ποδός, (''pous, podos'') "foot" is one of the three major groups (Clade, clades) of Dinosaur, dinosaurs, alon ...

and

Sauropodomorpha Sauropodomorpha ( ; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had lo ...

in the cladistic analysis undertaken on the genus when it was described, but remains squarely within

Saurischia Saurischia ( , meaning "reptile-hipped" from the Greek ' () meaning 'lizard' and ' () meaning 'hip joint') is one of the two basic divisions of dinosaurs (the other being Ornithischia), classified by their hip structure. Saurischia and Ornithi ...

as basal members of the order. An unnamed herrerasaurid from the

of Brazil was described and possibly belongs to a new morphotype of relatively large proportions, informally known as the "Big ''

Saturnalia Saturnalia is an Roman festivals, ancient Roman festival and holiday in honour of the List of Roman deities, god Saturn (mythology), Saturn, held on 17 December in the Julian calendar and later expanded with festivities until 19 December. By t ...

''". In the phylogenetic analysis within this study, herrerasaurids are recovered as non- eusaurischian saurischians.

Phylogeny

Fernando Novas (1992) defined Herrerasauridae as ''Herrerasaurus'', ''Staurikosaurus'', and their most recent common ancestor.

Paul Sereno Paul Callistus Sereno (born October 11, 1957) is a professor of paleontology at the University of Chicago who has discovered several new dinosaur species on several continents, including at sites in Inner Mongolia, Argentina, Morocco and Niger. ...

(1998) defined the group as the most inclusive clade including ''H. ischigualastensis'' but not ''

Passer domesticus The house sparrow (''Passer domesticus'') is a bird of the sparrow family Passeridae, found in most parts of the world. It is a small bird that has a typical length of and a mass of . Females and young birds are coloured pale brown and grey, ...

''. Langer (2004) provided first phylogenetic definition of a higher level

taxon In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

, Herrerasauria, as ''Herrerasaurus'' but not '' Liliensternus'' or ''

Plateosaurus ''Plateosaurus'' (probably meaning "broad lizard", often mistranslated as "flat lizard") is a genus of plateosaurid dinosaur that lived during the Late Triassic period, around 214 to 204 million years ago, in what is now Central and Northern Eu ...

''. According to current phylogenetic studies, all of these definitions describe the same clade. The first

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

presented follows one proposed analysis by Novas ''et al.'' in May 2011. In this review, ''Herrerasaurus'' is found to be a basal saurischian, but not a theropod. The second cladogram is based on an analysis by Sues ''et al.'' in April 2011. This review classified ''Herrerasaurus'' as a basal theropod. A large phylogenetic analysis of early dinosaurs by Matthew Baron, David Norman and Paul Barrett (2017) found Herrerasauridae within the clade

, as the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

. This was the result of the removal of

from Saurischia and its placement next to

Ornithischia Ornithischia () is an extinct clade of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. The name ''Ornithischia'', or "bird-hipped", reflects this similarity and is derived from the Greek ...

within the newly created clade

Ornithoscelida Ornithoscelida () is a proposed clade that includes various major groupings of dinosaurs. An order Ornithoscelida was originally proposed by Thomas Henry Huxley but later abandoned in favor of Harry Govier Seeley's division of Dinosauria into ...

. Baron & Williams (2018) found Herrerasauria (including ''

Daemonosaurus ''Daemonosaurus'' is an extinct genus of possible theropod dinosaur from the Late Triassic of New Mexico. The only known fossil is a skull and neck fragments from deposits of the latest Triassic Chinle Formation at Ghost Ranch. ''Daemonosaurus'' ...

'', '' Caseosaurus'' and ''

Saltopus ''Saltopus'' ("hopping foot") is a genus of very small bipedal dinosauriform containing the single species ''Saltopus elginensis'' from the late Triassic period of Scotland. It is one of the most famous Elgin Reptiles. Description ''Saltopu ...

'') outside Dinosauria. A similar result was provided by the phylogenetic analysis by Cau, 2018: Novas et al., 2021 revised the fossil record of

n early dinosaurs and supported that Herrerasauria is part of

but diverging earlier than both

, and further corroborated with the hypothesis that ''

'', ''

'' and '' Tawa'' are members of the clade. In 2024, Andrea Cau reclassified Herrerasauria within Theropoda.

Timeline of genera

ImageSize = width:1000px height:auto barincrement:15px PlotArea = left:10px bottom:50px top:10px right:10px Period = from:-251.9 till:-201 TimeAxis = orientation:horizontal ScaleMajor = unit:year increment:5 start:-251 ScaleMinor = unit:year increment:1 start:-251 TimeAxis = orientation:hor AlignBars = justify Colors = #legends id:CAR value:claret id:ANK value:rgb(0.4,0.3,0.196) id:HER value:teal id:HAD value:green id:OMN value:blue id:black value:black id:white value:white id:mesozoic value:rgb(0.54,0.54,0.258) id:triassic value:rgb(0.51,0.17,0.57) id:earlytriassic value:rgb(0.6,0.22,0.61) id:middletriassic value:rgb(0.73,0.53,0.71) id:latetriassic value:rgb(0.78,0.65,0.8) id:jurassic value:rgb(0.2,0.7,0.79) id:earlyjurassic value:rgb(0,0.69,0.89) id:middlejurassic value:rgb(0.52,0.81,0.91) id:latejurassic value:rgb(0.74,0.89,0.97) id:cretaceous value:rgb(0.5,0.78,0.31) id:earlycretaceous value:rgb(0.63,0.78,0.65) id:latecretaceous value:rgb(0.74,0.82,0.37) BarData= bar:eratop bar:space bar:periodtop bar:space bar:NAM1 bar:NAM4 bar:NAM3 bar:NAM2 bar:NAM5 bar:space bar:period bar:space bar:era PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25 shift:(7,-4) bar:periodtop from: -251.9 till: -251.2 color:earlytriassic text: Ind. from: -251.2 till: -247.2 color:earlytriassic text:

Olenekian In the geologic timescale, the Olenekian is an age (geology), age in the Early Triassic epoch (geology), epoch; in chronostratigraphy, it is a stage (stratigraphy), stage in the Lower Triassic series (stratigraphy), series. It spans the time betw ...

from: -247.2 till: -242 color:middletriassic text:

Anisian In the geologic timescale, the Anisian is the lower stage (stratigraphy), stage or earliest geologic age, age of the Middle Triassic series (stratigraphy), series or geologic epoch, epoch and lasted from million years ago until million years ag ...

from: -242 till: -237 color:middletriassic text: Ladinian from: -237 till: -227 color:latetriassic text:

from: -227 till: -208.5 color:latetriassic text:

from: -208.5 till: -201.3 color:latetriassic text:

Rhaetian The Rhaetian is the latest age (geology), age of the Triassic period (geology), Period (in geochronology) or the uppermost stage (stratigraphy), stage of the Triassic system (stratigraphy), System (in chronostratigraphy). It was preceded by the N ...

from: -201.3 till: -201 color:earlyjurassic bar:eratop from: -251.9 till: -247.2 color:earlytriassic text:

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 251.9 Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which ...

from: -247.2 till: -237 color:middletriassic text:

Middle Triassic In the geologic timescale, the Middle Triassic is the second of three epoch (geology), epochs of the Triassic period (geology), period or the middle of three series (stratigraphy), series in which the Triassic system (stratigraphy), system is di ...

from: -237 till: -201.3 color:latetriassic text:

from: -201.3 till: -201 color:earlyjurassic PlotData= align:left fontsize:M mark:(line,white) width:5 anchor:till align:left color:middletriassic bar:NAM1 from:-233.43 till:-233.23 text: Gnathovorax color:middletriassic bar:NAM4 from:-233.43 till:-233.23 text: Staurikosaurus color:middletriassic bar:NAM3 from:-231.6 till:-231.4 text: Sanjuansaurus color:middletriassic bar:NAM2 from:-231.4 till:-228.91 text:

Herrerasaurus ''Herrerasaurus'' is likely a genus of saurischian dinosaur from the Late Triassic period. Measuring long and weighing around , this genus was one of the earliest dinosaurs from the fossil record. Its name means "Herrera's lizard", after the ...

color:latetriassic bar:NAM5 from:-221.5 till:-212 text: Caseosaurus PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25 bar:period from: -251.9 till: -251.2 color:earlytriassic text: Ind. from: -251.2 till: -247.2 color:earlytriassic text:

from: -247.2 till: -242 color:middletriassic text:

from: -242 till: -237 color:middletriassic text: Ladinian from: -237 till: -227 color:latetriassic text:

from: -227 till: -208.5 color:latetriassic text:

from: -208.5 till: -201.3 color:latetriassic text:

from: -201.3 till: -201 color:earlyjurassic bar:era from: -251.9 till: -247.2 color:earlytriassic text:

from: -247.2 till: -237 color:middletriassic text:

from: -237 till: -201.3 color:latetriassic text:

from: -201.3 till: -201 color:earlyjurassic

References

{{Taxonbar, from=Q134186 Dinosaur families Carnian dinosaurs Dinosaurs of South America