Research history Early history In 1838, French zoologist
Henri Marie Ducrotay de Blainville made a review of palaeontological history and taxonomy as built upon from previous decades. Blainville recognized the importance of dentition in determining the affinities of fossil animals but criticized the overreliance of dental systems as automatically indicating taxonomic affinities. He then went on to examine reported fossil "
didelphids" (the taxonomic group now known as "
marsupials") in European land. He conducted reviews of fossils as previously described by Laizer and Parieu, concluding that
Hyaenodon is a valid genus based on its dentition but rejected the idea of it being a didelph based on its dental system and its
molars being closer in affinity to modern carnivorans. Blainville also mentioned a fossil of an upper jaw that the late
Georges Cuvier found and previously thought was close in affinity to the
Tasmanian devil (
Sarcophilus harrisii) of
New Holland (Australia). Previously, Cuvier presented the fossil to the
French Academy of Sciences in 1828 and thought that it was a large species of
thylacine (
Thylacinus cynocephalus) but died before he could make a formal description of it. Of note is that although the article of
Hyaenodon by Blainville was first written and published in 1838, it was not until a year later in 1839 when it was republished that Blainville added a footnote to the paragraph about the upper jaw. In it, he said that he restudied that fossil from the
Paris Basin and again was certain that it was a "monodelphian" (today
placental) predator, which he named
Pterodon dasyuroides. The genus name means "wing tooth" and is a combination of the
Ancient Greek words "" (wing) and "" (tooth). The etymology of the type species name derives from the Australian marsupial genus
Dasyurus and the Greek suffix "" meaning "like" due to apparent initial confusion of the genus affinity by Blainville. In 1841-1842, Blainville mentioned the genus
Pterodon but replaced the previous species name with
P. parisiensis. He also stated that despite thinking that the mammal did not have close affinities with
Dasyurus, he did not have sufficient skull material to prove what mammal group it was closest to. The species name is in reference to
Paris where its first fossil was found. In 1848-1852, however, he reclassified the species as
Hyaenodon requieni (having recognized the validity of the genus) and listed
P. dasyuroides as the only species of
Pterodon. In 1853, Pomel changed his position by recognizing the validity of
Hyaenodon, restoring the taxonomic affinities of species previously classified as belonging to it and therefore establishing that they no are no longer classified under
Pterodon (
H. leptorhynchus and
H. brachyrhynchus). He also reclassified
Taxotherium as a junior synonym of
Hyaenodon instead of
Pterodon. Within the genus
Pterodon, he recognized the species name
P. dasyuroides instead of
P. parisiensis and created two additional species based on dentition shapes and sizes:
P. cuvieri and
P. coquandi.
European hyaenodont revisions Gervais erected the species
P. exiguum in 1873 based on dentition with some similarities to both
Pterodon and
Hyaenodon but noted that it may constitute a new genus once he has more fossil material. The palaeontologist then corrected himself in 1876 by stating that the species belongs to
Hyaenodon as
H. exiguum, not
Pterodon. In 1876, Filhol recognized only
P. dasyuroides among all species previously erected for the genus and named a new species
P. biincisivus from the phosphorite deposits of
Escamps, France. He, in addition to confirming the taxonomic validities of the two species, erected a third named
P. quercyi in 1882. The French naturalist named a new species
Oxyaena galliæ based on dental remains being apparently similar to that of species of
Oxyaena previously described by
Edward Drinker Cope in the
Eocene deposits of
New Mexico, United States. in The same year, Filhol also reported that an individual whose last name was Pradines recently discovered anterior portions of the skull of
P. dasyuroides from the phosphate deposits of
Limogne-en-Quercy. English naturalist
Richard Lydekker made a review of known
pan-carnivoran genera in 1884, classifying them within the order Carnivora and rejecting Cope's classification of the members into the suborder
Creodonta within the order Bunotheria. While Cope originally assigned
Hyaenodon as the sole member of
Hyaenodontidae and
Pterodon plus
Oxyaena into
Oxyaenidae, Lydekker felt that
Pterodon was close in affinity to
Hyaenodon and therefore belonged in Hyaenodontidae. For
H. brachyhynchus, he listed
P. brachyhynchus,
P. requieni, and
H. requieni as junior synonyms. He also listed
P. leptorhynchus as a junior synonym of
H. leptorhynchus as well as
H. exiguus and
P. exiguus as synonyms of
H. vulpinus. For
Pterodon, he recognized
P. dasyuroides as the main valid species of the genus and listed
P. parisiensis as a definite synonym as well as
P. cuvieri and
P. coquandi as possible synonyms, although he did not invalidate
P. biincisivus. He also listed the species
Oxyæna galliæ but thought that the genus could be merged into
Pterodon due to minor dental differences and similarities to
P. biincisivus. Swiss palaeontologist
Ludwig Rütimeyer erected another species named
P. magnus in 1891 based on the larger dentition sizes compared to typical species of
Pterodon. However, in 1906, German scientist
Rudolf Martin said that he wanted to synonymize
P. magnum and the questionable
P. quercyi with
P. dasyuroides. He also listed
P. biincisivus as a synonym of
P. dasyuroides and stated that only one species is valid within
Pterodon. Additionally, he revalidated the species
O. galliæ but created the genus
Paroxyaena for it, arguing that because oxyaenids are very weakly represented in Europe compared to North America and that therefore the species' similarities to oxyaenids may have an instance of
convergent evolution. In 1979, Brigitte Lange-Badré made a systematic review of known hyaenodonts from Europe including
Pterodon. She listed
P. parisiensis,
P. cuvieri,
P. coquandi,
P. biincisivus, and
P. quercyi as synonyms of the only European species
P. dasyuroides. In addition, she listed
P. magnum as a synonym of
Paroxyaena galliae and listed
Hyaenodon exiguus as taking taxonomic priority over
H. vulpinus, therefore making the latter name and
P. exiguum synonyms. Many of the species classified or formerly classified to
Pterodon were of African or Asian origins.
Akhnatenavus leptognathus, "
Hyainailouros"
bugtiensis,
Orienspterodon dahkoensis, and
Neoparapterodon rechetovi. Several species names previously assigned to
Pterodon were later considered to be synonyms of
Hyaenodon species, namely "
P. exploratus" (=
H. incertus), "
P. californicus" (=
H. vetus), and "
P. mongoliensis" (=
H. mongoliensis). Additionally,
Hemipsalodon was made a synonym of
Pterodon by
Robert Joseph Gay Savage in 1965 while
Metapterodon was synonymized with it by
Leigh M. Van Valen in 1967, but the synonymies were unsupported by later authors. As a result of the synonymies, only one species assigned to
Pterodon remains pending reassessment to another genus:
P. hyaenoides, which is classified as belonging to the
Hyaenodontinae and is located in Asia. In 1999, A.V. Lavrov mentioned in his dissertation paper a genus he erected named "
Epipterodon" for which "
Pterodon"
hyaenoides would have been reclassified to. However, as the genus name has not yet been referenced and taxonomically validated in any peer-reviewed source, its name currently remains invalid.
Classification horridus'' of North America. The
Hyaenodontidae was recently determined to have been a separate lineage from the
Hyainailouridae.
Pterodon has historically been classified undisputedly as at least being within the clade of hyaenodonts within the later 20th century, later being included within the subfamily Hyainailourinae. In 2016, Matthew Borths et al. suggested that the Hyainailouridae had a close relationship with the
Teratodontinae and therefore arranged the superfamily
Hyainailouroidea to include them and include the
Proviverrinae, Hyaenodontidae, and North American hyaenodont groups. Compared to the proviverrines which never exceeded , the hyainailourines were much larger in size. This is because
P. dasyuroides does not form a natural clade with non-European species classified within the genus, therefore meaning that they are pending reassessments to other genera.
Pterodon sensu stricto (in a strict sense) made its appearance in western Europe by MP18 (late Eocene) in the form of
P. dasyuroides and lasted up to MP20.
P. dasyuroides was likely part of a ghost lineage of dispersing hyainailourines from Africa, and
Kerberos did not appear to have descended into
Pterodon or
Parapterodon. }} == Description==