| Eotephradactylus | |
|---|---|
 | |
| Reconstruction illustrating known material | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Ornithodira |
| Clade: | †Pterosauromorpha |
| Order: | †Pterosauria |
| Genus: | †Eotephradactylus Kligman et al.,2025 |
| Species: | †E. mcintireae |
| Binomial name | |
| †Eotephradactylus mcintireae Kligman et al., 2025 | |
Eotephradactylus (meaning "ash-winged dawn goddess") is anextinct genus ofpterosaurs known from theLate Triassic of what is nowArizona, United States. The genus contains asingle species,Eotephradactylus mcintireae, discovered in 2011 and named in 2025. It is known from part of the lower jaw, isolated teeth, and possibly a wing bone found in theChinle Formation, which dates to theNorian age. These bones were found in abone bed in addition to many other species, including various fish, mammal precursors, turtles, and other reptiles.
Eotephradactylus is anearly-diverging pterosaur, possibly closely related to the EuropeanSeazzadactylus. Like some other early pterosaurs, it is characterized by itsheterodont dentition. However, unique toEotephradactylus, it has extensive wear on all of its teeth, showing that it probably ate hard-shelled invertebrates or fish with mineralized scales.Eotephradactylus is the oldest known pterosaur named from North America.
In the summer of 2011, an expedition was conducted by theSmithsonian National Museum of Natural History andColumbia College Chicago in outcrops of the Owl Rock Member of theChinle Formation. These rock layers are located withinPetrified Forest National Park (PEFO) in northeastern Arizona, United States. This work, continued in 2012, 2015, and 2023, revealed abone bed, identified as PFV 393, preserving a high-diversity assemblage of fossil vertebrates. This locality and its specimens were briefly noted in aSociety of Vertebrate Paleontologyconferenceabstract in 2019.[1] Among the fossils identified from this locality were a partial leftmandible (lower jaw), isolated teeth, and aphalanx (digit bone) belonging to a pterosaur.[2]
In 2025, Kligman and colleaguesdescribedEotephradactylus mcintireae as a new genus and species of pterosaurs based on these fossil remains. They established PEFO 53384, part of the leftdentary bone preserving several teeth, as theholotype specimen. Two teeth, the multicusped PEFO 53536 andcaniniform PEFO 54092, were not found in association with the holotype. However, they share unique features with the holotype teeth, allowing for their referral toEotephradactylus. An isolated wing phalanx (finger bone), PEFO 52926, was also referred to this taxon on the assumption thatEotephradactylus is the only pterosaur present in the PFV 393 locality.[2]
Thegeneric name,Eotephradactylus, combines theGreek wordsἨώς (Eos), referring to themythic goddess of the dawn and the animal's position at the beginning of pterosaur evolution,τέφρα (tephra; "ash"), referring to the nearby volcanic ash layers, andδάκτυλος (daktylos; "digit"), in reference to the elongated wing-forming fourth finger in pterosaurs. The intended translation of this name is "ash-winged dawn goddess". Thespecific name,mcintireae, honors Suzanne McIntire, who discovered the fossil material in 2013 whilepreparing a block from the PFV 393 quarry.[2][3]
Eotephradactylus is notably one of the only Triassic pterosaurs found outside of Europe, and is the oldest pterosaur to be named from North America.[3][2]
As preserved, the holotype dentary ofEotephradactylus is 41 millimetres (1.6 in) long, although theanterior (toward the front) end is missing due to damage to the specimen. An impression in the matrix surrounding the dentary indicates the bone was at least 43.5 mm (1.71 in) long. In comparison, the dentary ofEudimorphodon is around 55 mm (2.2 in) long and its wingspan and body mass have been estimated at 1 m (3.3 ft) and 325 g (0.717 lb), respectively.[2] The body size ofEotephradactylus has been likened to that of a smallseagull.[3]
TheEotephradactylus dentary has at least 24alveoli (tooth sockets), 12 of which preserve erupted teeth. The dentary is shortest in the middle, expanding toward the front of the snout.Eotephradactylus is characterized by havingheterodont dentition in its dentary, with a combination of thin, pointedcaniniform teeth closer to the front of the snout and broader,cusped teeth toward the back of the jaws. In general, the teeth increase in labiolingual compression (becoming flatter) and mesiodistal length (broader) from front to back. The first two teeth preserved in the holotype are subconical in shape, though their incompleteness makes it impossible to identify the presence or absence of cusps (raised points on the tooth crown). As preserved, the third tooth bears three cusps and the fourth has one, although these are also incomplete. The fifth and sixth preserved teeth are smaller than those on either side and overlap from front to back. Both are likely tricuspid. Tooth seven (five cusps), eight (three cusps), and nine (six cusps) are all worn on their apices, so they may have born additional cusps. The tenth and eleventh teeth are the largest in the specimen and have seven and five cusps, respectively. Fluting (small grooves) is present directly mesial (toward the front) and distal (toward the back) to the central cusp on these teeth, which is identified as anautapomorphy (unique derived trait) ofEotephradactylus. The twelfth tooth is worn but likely had cusps, as evidenced by the presence of fluting.[2]
To test the affinities and relationships ofEotephradactylus, Kligman et al. (2025) scored the taxon in two separatephylogenetic datasets, both modified from the description of the early Argentinian pterosaursYelaphomte andPachagnathus by Martínez et al. (2022).[4] The first dataset, taken from Ezcurra et al. (2020),[5] broadly samples reptile diversity. This phylogenetic analysis confirmed that the fossils belonged to a pterosaur, and not another unrelated Triassic reptile. The analysis placedEotephradactylus as thesister taxon toEudimorphodon. However, Kligman et al. noted that, since this analysis only contained a limited number of pterosaur taxa and pterosaur-specific characters, the results were less likely to accurately indicate the precise affinities of the sampled taxa.[2]
The second dataset, taken from the Andres et al. (2014) description ofKryptodrakon,[6] is more directly focused on non-pterodactyloids, thus providing more accurate relationships within the early-diverging Pterosauria. These results recoveredEotephradactylus in apolytomy withSeazzadactylus, a clade includingEudimorphodon andArcticodactylus, theRaeticodactylidae, and theMacronychoptera (the clade including all other later-diverging pterosaurs). Thecladogram below displays these results:[2]
.png)
Most of theEotephradactylus teeth apices demonstrate extensive wear facets in theenamel, exposing thedentin within, another proposed autapomorphy of the taxon. This may indicate extensive tooth-toothocclusion or tooth-food contact. Specifically, it may suggest that the diet ofEotephradactylus included arthropods with hardened exoskeletons orpaleoniscoid fishes that have scales mineralized withganoine. Ganoine scales are the most common vertebrate fossil element found in the PFV 393 locality, strengthening this hypothesis.[2]
Eotephradactylus is known from the lower Owl Rock Member of theChinle Formation, which dates to the lateNorian stage of the lateTriassic period. More specifically, the fossil material was found in the PFV 393 assemblage, a bone bed of many vertebrate fossils.Radioisotopic dating usingU-Pb zircon crystals indicates anabsolute age of 209.187 ± 0.083 Ma for this layer. The geology of this locality consists of aconglomeraticmatrix withcarbonateclasts,allochthonous rock fragments, and medium to fine sands. The fossil-bearing conglomerates are associated with channels that indicate thedepositional environment was a largebraided river system that eroded into an underlyingfloodplain deposit. The poor sorting of the conglomerates suggests there may have been occasional periods of high energy, such as rapid episodes offlash flooding at the time the rock layers were deposited.[2]
Sixteen vertebrates have been identified from the PFV 393 bone bed, includingEotephradactylus. Thearchosauromorpha fauna is dominated by non-avemetatarsalians (the clade including pterosaurs and dinosaurs). This includes bones ofpseudosuchians (Revueltosaurus callenderi and arauisuchid)proterochampsians (Vancleavea campi and an unnameddoswelliid), aphytosaur, and an unnamedtrilophosaurid. Other reptiles include an unnamedsphenodontian (the group including the moderntuatara) andtestudinatan (turtle relative). Non-reptiliantetrapods include an unnamed carnivoroussynapsid (mammal 'precursor'), asalientianamphibian (species more closely related tofrogs than tosalamanders), andmetoposauridtemnospondyl. Various fish include ahybodont (shark relative),durophagous andpiscivorousactinopterygians includingpalaeoniscoids, and amawsoniid (a type ofcoelacanth).[2]
