Kongonaphon

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Kongonaphon
Temporal range: Mid to Late Triassic,
242–228  Ma
Kongonaphon life restoration.png
Life restoration
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Ornithodira
Clade: Pterosauromorpha
Family: Lagerpetidae
Genus: Kongonaphon
Kammerer et al., 2020
Type species
Kongonaphon kely
Kammerer et al., 2020

Kongonaphon is an extinct genus of lagerpetid avemetatarsalians from the Middle to Late Triassic of Madagascar. It contains a single species, Kongonaphon kely, which is known from a fragmentary partial skeleton. This fossil hails from the late Ladinian or early Carnian-age "basal Isalo II beds". As the first lagerpetid found in Africa, Kongonaphon extends the range of the family significantly. It possessed a combination of features from various other lagerpetids, but developed particularly long and slender leg bones. Kongonaphon is also the first lagerpetid for which fossils of the snout and teeth are known. It was likely an insectivore based on the shape and texture of its teeth. [1]

Contents

Kongonaphon is notable for its minuscule size, even compared to other small early avemetatarsalians. The proportionally elongated femur was only about 4 cm (1.6 inches) long, and the total height of the animal was estimated at around 10 cm (3.9 inches). Alongside other miniaturized archosaurs such as Scleromochlus , it suggests that avemetatarsalians experienced an abrupt reduction in size early in their evolution. This may explain the poor preservation and scarcity of early and middle Triassic avemetatarsalian fossils. A small size also may have helped them exploit a variety of new ecological niches. The most successful avemetatarsalian subgroups, pterosaurs and dinosaurs, may have evolved as a result of this abrupt size reduction. Miniaturization has been correlated with the evolution of flight (a defining feature of pterosaurs) and the acquisition of bipedalism (which was utilized by many dinosaurs). It would also lead to poor heat retention, encouraging the evolution of feathers or other filamentous structures.

Although Kongonaphon is clearly an ornithodiran, there is uncertainty whether it was closer to pterosaurs or dinosaurs. When placed in a phylogenetic analysis without Scleromochlus, lagerpetids are found to be basal dinosauromorphs (closer to dinosaurs). However, the inclusion of Scleromochlus leads to the analysis tentatively supporting lagerpetids as pterosauromorphs (closer to pterosaurs). [1] Fossil remains from other lagerpetids described in late 2020 strongly support the hypothesis that lagerpetids were pterosauromorphs. [2] [3]

Discovery

Kongonaphon is based on UA 10618, a partial skeleton. The disarticulated skeleton was split between two sandstone blocks, which also preserve a jaw of the rhynchosaur Isalorhynchus.Kongonaphon is the first lagerpetid to have skull material published, as part of a maxilla has been preserved in UA 10618. The fossil also contains a mostly complete femur alongside a caudal (tail) vertebra, foot bones, fragments of the tibia and fibula, and a potential humerus fragment. [1]

The skeleton was recovered in 1998 [4] from a productive fossil site in the Morondava Basin of southwest Madagascar. The site preserves the lower part of the informally named Isalo II beds (also known as the Makay Formation). The basal Isalo II beds are likely late Ladinian or early Carnian in age based on cynodonts shared with the Santa Maria Supersequence of Brazil. [1]

Kongonaphon was first reported in a 2019 conference abstract, though at the time it was unnamed. [5] It was formally named and described in 2020. The generic name is derived from the Malagasy word Kongona (meaning "bug"), and the Greek suffix -phon (derived from a term for "slayer"). The specific name kely is the Malagasy word for "small". Together, Kongonaphon kely translates to "tiny bug slayer", according to its diminutive size and potentially insectivorous habits. [1]

Description

The maxilla is tall and has a relatively wide front portion when seen from above. The front edge is also concave, similar to early pterosaurs. Six teeth are preserved in the maxilla, though the rear part of the bone is missing. The teeth were peg-like and conical, with a circular cross-section and no serrations. The teeth are ornamented by irregular pitting, a texture which in modern animals is correlated with a diet of insects. A limb bone fragment has been tentatively identified as the lower part of a humerus. This fragment has poorly differentiated condyles (unlike the humerus of Ixalerpeton ) but is also markedly asymmetrical (like Ixalerpeton). [1]

The femur is very slender, sigmoid, and has a prominent fourth trochanter. The femoral head shares many similarities with other lagerpetids. It is strongly hooked and has a concave emargination on its lower edge. When seen from above, the femoral head has a large posteromedial tuber, a small anterolateral tuber, and no anteromedial tuber. The outer side of the femoral head also has an anterior trochanter, a muscle scar which is present in some lagerpetids but absent in others. At least in Dromomeron gregorii , it seems to develop only in fully grown individuals. The blade-like fourth trochanter has a folded inner edge and an outer edge which smoothly transitions to the shaft of the femur. Both of these features are more similar to Ixalerpeton than Lagerpeton (or Dromomeron, which has a fourth trochanter which is small and mound-like in some species and absent in others). The bent inner edge of the fourth trochanter overlooks a depression which is split in two by a thin ridge. The femur is extended and narrows significantly towards its broken and eroded lower extremity. This contrasts with other lagerpetids, which have a femur that expands towards the knee. [1]

Tibia fragments are slightly curved and expanded near the knee, similar to other lagerpetids. A pair of long and closely appressed bones have been identified as metatarsals, though this is uncertain due to the unusually bent appearance of one of the bones. Pedal phalanges (toe bones) are hourglass-shaped and have strongly developed joints. The long and narrow caudal (tail) vertebra has a concave lower edge and fused neurocentral sutures. [1]

Classification

To test its relationships to other reptiles, Kongonaphon was placed in a phylogenetic analysis modified from Müller et al. 2019. [6] This analysis did not originally include Scleromochlus , a tiny archosaur often considered distantly related to pterosaurs. The first iteration of the analysis found Kongonaphon and other lagerpetids to be the earliest-diverging dinosauromorphs, more closely related to dinosaurs than to pterosaurs. This result is common among archosaur-focused analyses. The following cladogram illustrates the first iteration: [1]

Avemetatarsalia

Scleromochlus was added in the second iteration of the analysis. Unusually, lagerpetids shifted from dinosauromorphs to pterosauromorphs (closer to pterosaurs) in this iteration. Pterosauromorpha is justified by several synapomorphies (shared derived characteristics) of the maxilla and ankle, though some of these are unknown in lagerpetids. As a result, further study is required to justify the placement of lagerpetids within Pterosauromorpha. This is also the case for Scleromochlus, which is coded into the analysis based on latex casts of sandstone molds. The following cladogram illustrates the second iteration: [1]

Avemetatarsalia

Paleobiology

The teeth of Kongonaphon are similar to those of insect-eating modern animals in both shape and texture. This is among the most convincing evidence for an insectivorous diet in early avemetatarsalians, especially lagerpetids (for which teeth were previously unknown). [1] This diet has also been suggested for Silesaurus based on referred coprolites, [8] but Silesaurus's tooth wear suggests it was primarily herbivorous. [9]

Histology and development

A histological study on a tibia fragment of UA 10618 has helped clarify the animal's bone structure, growth, and development. The tibia is fairly thin-walled, with a cortex (dense outer layer) making up about 20% of the diameter. Vascular canals are common in the cortex, and are primarily longitudinally oriented (parallel to the bone's shaft and circular in cross-section). There is some organized anastomosing (branching) along canals in the mid-cortex. The branching canals appear to radiate towards the outer cortex, a trait also observed in the bones of Dromomeron romeri . Bone fibers are oriented parallel to the circumference of the bone in the outer cortex, indicating slower growth. Further into the cortex they are more disorganized, indicating fast early growth. Two lines of arrested growth, typically indicators of annual scarcity, are developed in the inner cortex. Osteocyte lacunae are oval-shaped and randomly distributed. [1]

Despite its tiny size, histology supports the idea that the Kongonaphon individual was not a hatchling or young juvenile. Parallel-fibered bone, lines of arrested growth, and flattened osteocyte lacunae are all correlated with the animal having been alive for quite some time prior to dying and becoming fossilized. The first characteristic in particular suggests that its growth was slower than early pterosaurs or dinosaurs. Other skeletal features also suggest that the individual was an adult. These including fused neurocentral sutures on the vertebra and smoothly textured limb bones. Additionally, several characteristics of Kongonaphon's femur are absent in young individuals of certain other lagerpetid species. Nevertheless, a lack of remodeling and widely distributed vascular canals indicate that the animal was still growing. This means that other individuals perhaps may have been able to grow slightly larger. [1]

Related Research Articles

<i>Scleromochlus</i> Extinct genus of reptiles

Scleromochlus is an extinct genus of small pterosauromorph archosaurs from the Late Triassic Lossiemouth Sandstone of Scotland. The genus contains the type and only species Scleromochlus taylori, named by Arthur Smith Woodward in 1907.

<i>Marasuchus</i> Extinct genus of reptiles

Marasuchus is a genus of basal dinosauriform archosaur which is possibly synonymous with Lagosuchus. Both genera lived during the Late Triassic in what is now La Rioja Province, Argentina. Marasuchus contains a single species, Marasuchus lilloensis.

<i>Azendohsaurus</i> Genus of herbivorous Triassic reptile

Azendohsaurus is an extinct genus of herbivorous archosauromorph reptile from roughly the late Middle to early Late Triassic Period of Morocco and Madagascar. The type species, Azendohsaurus laaroussii, was described and named by Jean-Michel Dutuit in 1972 based on partial jaw fragments and some teeth from Morocco. A second species from Madagascar, A. madagaskarensis, was first described in 2010 by John J. Flynn and colleagues from a multitude of specimens representing almost the entire skeleton. The generic name "Azendoh lizard" is for the village of Azendoh, a local village near where it was first discovered in the Atlas Mountains. It was a bulky quadruped that unlike other early archosauromorphs had a relatively short tail and robust limbs that were held in an odd mix of sprawled hind limbs and raised forelimbs. It had a long neck and a proportionately small head with remarkably sauropod-like jaws and teeth.

<i>Lagerpeton</i> Extinct genus of reptiles

Lagerpeton is a genus of lagerpetid avemetatarsalian, comprising a single species, L. chanarensis. First described from the Chañares Formation of Argentina by A. S. Romer in 1971, Lagerpeton's anatomy is somewhat incompletely known, with fossil specimens accounting for the pelvic girdle, hindlimbs, posterior presacral, sacral and anterior caudal vertebrae. Skull and shoulder material has also been described.

<i>Teleocrater</i> Extinct genus of reptiles

Teleocrater is a genus of avemetatarsalian archosaur from the Middle Triassic Manda Formation of Tanzania. The name was coined by English paleontologist Alan Charig in his 1956 doctoral dissertation, but was only formally published in 2017 by Sterling Nesbitt and colleagues. The genus contains the type and only species T. rhadinus. Uncertainty over the affinities of Teleocrater have persisted since Charig's initial publication; they were not resolved until Nesbitt et al. performed a phylogenetic analysis. They found that Teleocrater is most closely related to the similarly enigmatic Yarasuchus, Dongusuchus, and Spondylosoma in a group that was named the Aphanosauria. Aphanosauria was found to be the sister group of the Ornithodira, the group containing dinosaurs and pterosaurs.

<span class="mw-page-title-main">Dinosauromorpha</span> Clade of reptiles

Dinosauromorpha is a clade of avemetatarsalians that includes the Dinosauria (dinosaurs) and some of their close relatives. It was originally defined to include dinosauriforms and lagerpetids, with later formulations specifically excluding pterosaurs from the group. Birds are the only dinosauromorphs which survive to the present day.

<span class="mw-page-title-main">Avemetatarsalia</span> Clade of archosaur reptiles

Avemetatarsalia is a clade of diapsid reptiles containing all archosaurs more closely related to birds than to crocodilians. The two most successful groups of avemetatarsalians were the dinosaurs and pterosaurs. Dinosaurs were the largest terrestrial animals for much of the Mesozoic Era, and one group of small feathered dinosaurs has survived up to the present day. Pterosaurs were the first flying vertebrates and persisted through the Mesozoic before dying out at the Cretaceous-Paleogene (K-Pg) extinction event. Both dinosaurs and pterosaurs appeared in the Triassic Period, shortly after avemetatarsalians as a whole. The name Avemetatarsalia was first established by British palaeontologist Michael Benton in 1999. An alternate name is Pan-Aves, or "all birds", in reference to its definition containing all animals, living or extinct, which are more closely related to birds than to crocodilians.

<span class="mw-page-title-main">Pterosauromorpha</span> Extinct clade of reptiles

Pterosauromorpha is one of the two basic divisions of Ornithodira that includes pterosaurs and all taxa that are closer to them than to dinosaurs and their close relatives. In addition to pterosaurs, Pterosauromorpha also includes the basal clade Lagerpetidae and some other Late Triassic ornithodirans.

<span class="mw-page-title-main">Ornithosuchidae</span> Extinct family of reptiles

Ornithosuchidae is an extinct family of pseudosuchian archosaurs from the Triassic period. Ornithosuchids were quadrupedal and facultatively bipedal, meaning that they had the ability to walk on two legs for short periods of time. They had distinctive, downturned snouts, unique, "crocodile-reversed" ankle bones, and several other features that distinguish them from other archosaurs. Ornithosuchids were geographically widespread during the Carnian and Norian stages of the Late Triassic with members known from Argentina, Brazil, and the United Kingdom. Four genera, comprising Ornithosuchus, Venaticosuchus, Dynamosuchus, and Riojasuchus are presently known. The family was first erected by German paleontologist Friedrich von Huene in 1908.

<i>Dromomeron</i> Extinct genus of reptiles

Dromomeron is a genus of lagerpetid avemetatarsalian which lived around 220 to 211.9 ± 0.7 million years ago. The genus contains species known from Late Triassic-age rocks of the Southwestern United States and northwestern Argentina. It is described as most closely related to the earlier Lagerpeton of Argentina, but was found among remains of true dinosaurs like Chindesaurus, indicating that the first dinosaurs did not immediately replace related groups.

<i>Asilisaurus</i> Genus of reptiles (fossil)

Asilisaurus ; from Swahili, asili, and Greek, σαυρος is an extinct genus of silesaurid archosaur. The type species is Asilisaurus kongwe. Asilisaurus fossils were uncovered in the Manda Beds of Tanzania and date back to the early Carnian, making it one of the oldest known members of the Avemetatarsalia. It was the first non-dinosaurian dinosauriform recovered from Africa. The discovery of Asilisaurus has provided evidence for a rapid diversification of avemetatarsalians during the Middle Triassic, with the diversification of archosaurs during this time previously only documented in pseudosuchians.

<span class="mw-page-title-main">Lagerpetidae</span> Extinct family of reptiles

Lagerpetidae is a family of basal avemetatarsalians. Though traditionally considered the earliest-diverging dinosauromorphs, fossils described in 2020 suggest that lagerpetids may instead be pterosauromorphs. Lagerpetid fossils are known from the Triassic of Argentina, Arizona, Brazil, Madagascar, New Mexico, and Texas. They were typically small, although some lagerpetids, like Dromomeron gigas and a specimen from the Santa Rosa Formation attributed to Dromomeron sp., were able to get quite large. Lagerpetid fossils are rare; the most common finds are bones of the hindlimbs, which possessed a number of unique features.

Faxinalipterus is a genus of ornithodiran archosaur, originally described as a pterosaur, from the Late Triassic Caturrita Formation of southern Brazil. A study from 2022 reinterpreted the fossil remains and instead suggests them to belong to a member of the Lagerpetidae, another clade of pterosauromorphs.

<i>Diodorus scytobrachion</i> Extinct species of reptile

Diodorus is a genus of silesaurid dinosauromorph that lived during the Late Triassic in what is now Morocco. Fossils were discovered in the Timezgadiouine Formation of the Argana Basin, and were used to name the new genus and species Diodorus scytobrachion. The genus name honors the mythological king Diodorus and the ancient historian Diodorus Siculus; the specific name is ancient Greek for 'leathery arm' and also honors the mythographer Dionysius Scytobrachion. The holotype specimen is a partial dentary bone (front of the lower jaw), and assigned specimens include isolated teeth, two humeri (upper arm bones), a metatarsal (foot bone), and femur (thigh bone).

<i>Buriolestes</i> Extinct genus of dinosaurs

Buriolestes is a genus of early sauropodomorph dinosaurs from the Late Triassic Santa Maria Formation of the Paraná Basin in southern Brazil. It contains a single species, B. schultzi, named in 2016. The type specimen was found alongside a specimen of the lagerpetid dinosauromorph Ixalerpeton.

Ixalerpeton is a genus of lagerpetid avemetatarsalian containing one species, I. polesinensis. It lived in the Late Triassic of Brazil alongside the sauropodomorph dinosaur Buriolestes.

Aphanosauria is an extinct group of reptiles distantly related to dinosaurs. They are at the base of a group known as Avemetatarsalia, one of two main branches of archosaurs. The other main branch, Pseudosuchia, includes modern crocodilians. Aphanosaurs possessed features from both groups, indicating that they are the oldest and most primitive known clade of avemetatarsalians, at least in terms of their position on the archosaur family tree. Other avemetatarsalians include the flying pterosaurs, small bipedal lagerpetids, herbivorous silesaurids, and the incredibly diverse dinosaurs, which survive to the present day in the form of birds. Aphanosauria is formally defined as the most inclusive clade containing Teleocrater rhadinus and Yarasuchus deccanensis but not Passer domesticus or Crocodylus niloticus. This group was first recognized during the description of Teleocrater. Although only known by a few genera, Aphanosaurs had a widespread distribution across Pangaea in the Middle Triassic. They were fairly slow quadrupedal long-necked carnivores, a biology more similar to basal archosaurs than to advanced avemetatarsalians such as pterosaurs, lagerpetids, and early dinosaurs. In addition, they seemingly possess 'crocodile-normal' ankles, showing that 'advanced mesotarsal' ankles were not basal to the whole clade of Avemetatarsalia. Nevertheless, they possessed elevated growth rates compared to their contemporaries, indicating that they grew quickly, more like birds than other modern reptiles. Despite superficially resembling lizards, the closest modern relatives of aphanosaurs are birds.

<i>Kwanasaurus</i> Extinct genus of silesaurid dinosauromorph reptiles

Kwanasaurus is an extinct genus of silesaurid dinosauromorph reptiles from the Late Triassic of Colorado. It is known from a single species, Kwanasaurus williamparkeri. Kwanasaurus had a deeper, stronger skull and greater specialization for herbivory compared to other silesaurids. It also possessed many unique characteristics of the snout, ilium, and lower part of the femur. It was described along with new specimens of Dromomeron from the Eagle Basin, the northernmost extent of the Chinle Formation.

Isalo II, also known as the Makay Formation, is an informal Triassic geological unit in Madagascar.

<i>Venetoraptor</i> Genus of lagerpetid archosaurs

Venetoraptor is an extinct genus of lagerpetid archosaurs from the Late Triassic Santa Maria Formation of Rio Grande do Sul, Brazil. The genus contains a single species, V. gassenae, known from a partial skeleton.

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