Candidodontidae is 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 ...

notosuchia Notosuchia is a suborder of primarily Gondwanan mesoeucrocodylian crocodylomorphs that lived during the Jurassic and Cretaceous. Some phylogenies recover Sebecosuchia as a clade within Notosuchia, others as a sister group (see below); if Sebecosu ...

crocodyliform Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the only pseudo ...

s. It was originally used in 2002 as a name for a

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, ...

that includes the

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

Araripesuchus ''Araripesuchus'' is a genus of extinct crocodyliform that existed during the Cretaceous period of the late Mesozoic era some 125 to 66 million years ago. Six species of ''Araripesuchus'' are currently known. They are generally considered to be n ...

'', ''

Candidodon ''Candidodon'' is an extinct genus of notosuchian mesoeucrocodylian. Fossils have been found in the Early Cretaceous Itapecuru Formation in Brazil. Description The genus is characterized by a particularly elongate pair of choanae in its pala ...

'', and ''

Malawisuchus ''Malawisuchus'' (meaning "Malawi crocodile") is an extinct genus of notosuchian mesoeucrocodylian from the Early Cretaceous Dinosaur Beds of Malawi. It was described in 1997 by Elizabeth Gomani as a member of the family Notosuchidae. The type ...

''. Later in 2004 the family was formally defined as a

node-based taxon Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional approach, in which taxon names are defined by a '' type'', which ...

including ''Candidodon itapecuruense'' and ''

Mariliasuchus amarali ''Mariliasuchus'' ("Marilia crocodile") is an extinct genus of Late Cretaceous notosuchian mesoeucrocodylian found near Marilia, Brazil. The first bone remains were found and collected in 1995 by Brazilian paleontologist William Nava, in red r ...

''. A 2009 study redefined Candidodontidae as a

stem-based taxon Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional approach, in which taxon names are defined by a '' type'', which ...

which included ''Candidodon'', ''Malawisuchus'', and possibly ''Mariliasuchus''.

Phylogenetics

The first formal definition of the family does not fit well with many

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 ...

studies of notosuchians that place ''Candidodon'' and ''Mariliasuchus'' far apart. If this definition were to be used, Candidodontidae would include the last common ancestor of ''Candidodon'' and ''Mariliasuchus'' and all of its descendants. According to these studies, these descendants would include many other genera and families, some of which were named before Candidodontidae and thus would have priority over it. A new definition was given in 2009 in which Candidodontidae was considered a stem-based taxon. Under this definition, Candidodontidae includes all taxa more closely related to ''Candidodon itapecuruensis'' than to ''

Notosuchus terrestris ''Notosuchus'' (; 'southern crocodile') is an extinct genus of South American notosuchian crocodylomorph. It was terrestrial, living approximately 85 million years ago in the Santonian stage of the Late Cretaceous. Description ''Notosuchus'' wa ...

'', '' Uruguaysuchus aznarezi'', '' Comahuesuchus brachybuccalis'', '' Sphagesaurus huenei'', ''

Baurusuchus pachecoi ''Baurusuchus'' is an extinct member of the ancestral crocodilian lineage, which lived in Brazil from 90 to 83.5 million years ago, in the Late Cretaceous period. Technically, it is a genus of baurusuchid mesoeucrocodylian. It was a terrest ...

'', and ''

Crocodylus niloticus ''Crocodylus'' is a genus of true crocodiles in the family Crocodylidae. Taxonomy The generic name, ''Crocodylus'', was proposed by Josephus Nicolaus Laurenti in 1768. ''Crocodylus'' contains 13–14 extant (living) species and 5 extinct species ...

''. The number of species that are less closely related to these taxa are called specifiers, and were used to insure that Candidodontidae did not become overly inclusive if ''Candidodon'' was placed in a different phylogenetic position in the future. According to the 2009 study, Candidodontidae included ''Candidodon'', ''Malawisuchus'', and possibly ''Mariliasuchus''. However, the 2018 cladistic analysis of ''

Roxochampsa ''Roxochampsa'' is an extinct genus of crocodylomorph from the Late Cretaceous of Brazil belonging to the sebecosuchian clade Itasuchidae. The type species is ''R. paulistanus''. Discovery and naming ''Roxochampsa'' was originally described ...

'' recovered ''Mariliasuchus'' as a close relative of

Sphagesauridae Sphagesauridae is a Gondwanan family of mesoeucrocodylians that lived during the Late Cretaceous. It was a clade of terrestrial crocodilians that evolved very mammal-like teeth and jaws.MARINHO, T.S. & CARVALHO, I.S. Revision of the Sphagesaurida ...

.Piacentini Pinheiro AE, Pereira PVLGdC, de Souza RG, Brum AS, Lopes RT, Machado AS, et al. (2018) Reassessment of the enigmatic crocodyliform "Goniopholis" paulistanus Roxo, 1936: Historical approach, systematic, and description by new materials. PLoS ONE 13(8): e0199984. https://doi.org/10.1371/journal.pone.0199984

Description

Members of Candidodontidae can be defined on the basis of

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 ...

, characteristics shared between taxa and present in their most recent common ancestor. When the family was first defined, several synapomorphies were used to diagnose it. For example, one

synapomorphy 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 ...

was the large size of the

supratemporal fenestrae The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

, two holes that occupy most of the surface of the

skull roof The skull roof, or the roofing bones of the skull, are a set of bones covering the brain, eyes and nostrils in bony fishes and all land-living vertebrates. The bones are derived from dermal bone and are part of the dermatocranium. In comparati ...

. Another synapomorphy was the similar size and shape of the postcaniniform teeth, those that are behind the

caniniform In mammalian oral anatomy, the canine teeth, also called cuspids, dog teeth, or (in the context of the upper jaw) fangs, eye teeth, vampire teeth, or vampire fangs, are the relatively long, pointed teeth. They can appear more flattened howeve ...

s and in front of the molariforms. The distance between the front of the eye sockets and the tip of the snout is greater than or equal to the distance between the front of the eye sockets and the back of the skull. Inside the skull, the internal nares are not separated from one another. The 2009 definition was from a study that focused on the teeth of notosuchians. Several features of the teeth of candidodontids were identified. These include a constricted

crown A crown is a traditional form of head adornment, or hat, worn by monarchs as a symbol of their power and dignity. A crown is often, by extension, a symbol of the monarch's government or items endorsed by it. The word itself is used, partic ...

base, a bulbous shape to the tooth, and several distinctive cusps. In candidodontids, namely ''Candidodon'' and ''Malawisuchus'', there is a main cusp and several smaller cusps surrounding it.

References

Terrestrial crocodylomorphs Early Cretaceous crocodylomorphs Early Cretaceous first appearances Cretaceous extinctions Prehistoric reptile families {{paleo-archosaur-stub zh:坎迪多齒鱷