''Lutungutali'' (meaning "high hip" in the Bemba language) is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of silesaurid

dinosauriform Dinosauromorpha is a clade of avemetatarsalian archosaurs (reptiles closer to birds than to crocodilians) that includes the Dinosauria (dinosaurs) and some of their close relatives. It was originally defined to include dinosauriforms and lager ...

from the

Middle Triassic In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided in chronostratigraphy. The Middle Triassic spans the time between Ma and ...

of Zambia. The single

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

of the genus is ''Lutungutali sitwensis''. ''Lutungutali'' was named in 2013 and described from a fossil specimen,

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

NHCC LB32, including hip bones and tail vertebrae. The specimen was collected in 2009 from the upper Ntawere Formation, which dates to the

Anisian In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million years ago. The Anisian Age succeeds the Olenekian Age (part of the Lower Triassic Ep ...

stage of the Middle Triassic. ''Lutungutali'' is the first known silesaurid from Zambia and, along with the Tanzanian silesaurid '' Asilisaurus'' and dinosauriform '' Nyasasaurus'', the oldest bird-line

archosaur Archosauria () is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of the term which includes birds. Extinct archosaurs include non-avian d ...

known from body fossils (i.e. parts of the skeleton).

Description

''Lutungutali'' is known from parts of its

pelvis The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The ...

and from four caudal vertebrae that make up the base of the tail. These bones represent one individual, although bones that may belong to ''Lutungutali'' representing eight other individuals were collected from the same fossil site in 2011. ''Lutungutali'' shares the following three features (

synapomorphies In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have ...

) with other early dinosauriforms: * A small area over which the pubis and

ischium The ischium () form ...

bones of the hip connect. * A depression or

fossa Fossa may refer to: Animals * Fossa (animal), the common name of a carnivoran mammal of genus ''Cryptoprocta'' endemic to Madagascar * ''Fossa'', the Latin genus name of the Malagasy civet, a related but smaller mammal endemic to Madagascar Pla ...

on the ischium where it connects with the pubis and ilium. * The length of the ischium exceeding the length of the iliac blade across the top of the hip. ''Lutungutali'' also shares two synapomorphies with the

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

or evolutionary grouping containing silesaurids and dinosaurs: * A crest of bone extending upward from the supraacetabular crest (a bony ridge above the

acetabulum The acetabulum (), also called the cotyloid cavity, is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint. Structure There are three bones of the ''os coxae'' (hip bone) that c ...

or hip socket) that joins with the preacetabular process, the forward-most projection of the iliac blade. * A lengthy connection between the two pairs of ischia, except for a division of the two bones near their connection with the rest of the hip. In addition, it shares two synapomorphies with other silesaurids: * A straight lower margin of the hip socket on the ilium (more basal dinosauriforms have a convex margin, and dinosaurs have a concave margin). * The lack of a ridge of bone behind the hip socket called the antitrochanter. ''Lutungutali'' has one unique feature or

autapomorphy In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to t ...

that distinguishes it from all other dinosauriforms: an iliac blade that is taller than the portion of the ilium that forms the hip socket. This feature is references in its name, which means "high hip" in the Bemba Language.

Phylogeny and evolutionary significance

''Lutungutali'' belongs to Silesauridae, a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

of archosaurs that is very closely related to Dinosauria. Silesaurids are known from southern Africa, Poland, the southwestern United States, and South America. When ''Lutungutali'' was named in 2013, a

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analysis (an analysis of evolutionary relationships) grouped it with the most

derived Derive may refer to: * Derive (computer algebra system), a commercial system made by Texas Instruments * ''Dérive'' (magazine), an Austrian science magazine on urbanism *Dérive, a psychogeographical concept See also * *Derivation (disambiguatio ...

silesaurids from 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 ...

. The closest silesaurid in both space and time to ''Lutungutali'' is ''Asilisaurus'' from the Anisian-age Manda Beds of Tanzania, yet it was found to be a more

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

silesaurid. Below is a cladogram from the analysis: ''Lutungutali'' and ''Asilisaurus'' are the two oldest known members of Avemetatarsalia, the line of archosaurs that includes birds. The oldest known member of the other line of archosaurs, Pseudosuchia (crocodile-line archosaurs), is from the Olenekian stage of the

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

, meaning that the first members of Avemetatarsalia must have appeared by this time. However, before the discovery of ''Asilisaurus'' (which was named in 2010), the oldest known avemetatarsalians were from the

Ladinian The Ladinian is a stage and age in the Middle Triassic series or epoch. It spans the time between Ma and ~237 Ma (million years ago). The Ladinian was preceded by the Anisian and succeeded by the Carnian (part of the Upper or Late Triassic). ...

stage of the Middle Triassic. Because ''Asilisaurus'' and ''Lutungutali'' are relatively

members of Avemetatarsalia, their presence in the Anisian stage of the Middle Triassic suggests that avemetatarsalians underwent a rapid diversification at a time in their evolutionary history that was earlier than previously thought.

References

{{Taxonbar, from=Q16754562 Silesaurids Anisian genera Middle Triassic reptiles of Africa Fossils of Zambia Fossil taxa described in 2013 Taxa named by Sterling Nesbitt Taxa named by Christian Sidor