Thalassodromids Temporal range:Albian PreꞒ Ꞓ O S D C P T J K Pg N
Replica skeleton ofTupuxuara leonardii
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	†Pterosauria
Suborder:	†Pterodactyloidea
Clade:	†Azhdarchoidea
Family:	†Thalassodromidae Witton, 2009
Type species
†Thalassodromeus sethi Kellner & Campos, 2002
Genera
†Banguela? †Kariridraco †Thalassodromeus †Tupuxuara
Synonyms
Thalassodrominae Kellner, 2007 Tupuxuaridae Martill, Bechly & Heads, 2007

Thalassodromidae (meaning "sea runners") is a group ofazhdarchoidpterosaurs from theEarly Cretaceous (Albian) ofBrazil. All known definitive members come from theRomualdo Formation ofBrazil, which include thetype genusThalassodromeus, as well asTupuxuara andKariridraco. Proposals of additional thalassodromid genera from theLate Cretaceous are controversial and have not been supported.

The classification of Thalassodromidae is quite controversial and disputed. It was initially denominatedThalassodrominae, as a subfamily within the groupTapejaridae. However, opposing studies regarding its placement have argued that its members were more closely related toazhdarchids anddsungaripterids, while also elevating it to family level. Though the relationship with tapejarids remains supported by many studies, it has been proposed that it is preferable to retain them as a distinct family for consistency of communication.

The classification of thalassodromids is controversial. Its initial members includedThalassodromeus andTupuxuara, which were assigned initially to the familyTapejaridae by Brazilian paleontologistsAlexander Kellner and Diógenes de Almeida Campos. In 2007, the subfamily Thalassodrominae was coined by Kellner to group both members within Tapejaridae.^[1]

However, a conflicting phylogenetic model emerged arguing that bothThalassodromeus andTupuxuara were more closely related to the familyAzhdarchidae instead of the tapejarids. As early as 2003, paleontologist David Unwin created the groupNeoazhdarchia to containTupuxuara and Azhdarchidae.^[2] This arrangement would later be supported by British paleontologistsDavid Martill andDarren Naish, who deemed Tapejaridae to beparaphyletic (unnatural), and found bothThalassodromeus andTupuxuara assister taxa to Azhdarchidae.^[3] In 2008, Chinese paleontologistLü Junchang and colleagues would use the term "Tupuxuaridae" to include both genera in theirphylogenetic analysis, finding the group nested within Neoazhdarchia.^[4] In 2009, British paleontologistMark Witton also concurred with the placement ofThalassodromeus andTupuxuara within Neoazhdarchia. However, he noted that the term Thalassodrominae was created before Tupuxuaridae, so therefore it had naming priority. He elevated Thalassodrominae to family level to satisfy the hierarchy within Neoazhdarchia, thus creating the denomination Thalassodromidae.^[5] Phylogenetic analyses by Brian Andres in 2014 and 2021 would support this model, finding a relationship between Thalassodromidae andDsungaripteridae within Neoazhdarchia, a conclusion also found by a 2018 study.^[6][7][8][9]

Many studies, however, have retained the original model of Thalassodrominae as a subfamily of Tapejaridae. In 2011 a study Brazilian paleontologist Felipe Pinheiro and colleagues retained the conception and expanded it to includeChaoyangopterinae, considered by other studies to be a distinct family.^[10] Studies by Rodrigo Pêgas and colleagues,^[11][12] Gabriela Cerquiera and colleagues,^[13][14] as well as Kellner himself have continued to followed Kellner's original model, into the 2020s,^[15][16] amongst others.^[17][18] Despite continuing to favour the close relationship ofThalassodromeus andTupuxuara withTapejara and its relatives, Pêgas and colleagues began to advocate for the use of Thalassodromidae rather than Thalassodrominae for sake of consistency between studies that do and do not find this relationship. Under this nomenclatural model, they are both families withinTapejaromorpha.^[19] Subsequent studies by Pêgas and colleagues would follow this change,^[12][20] though others continue to use the traditional scope of Tapejaridae.^[14][16]

In 2018, paleontologist Nicholas Longrich and colleagues recovered the pterosaursAerotitan andAlanqa as thalassodromids, but noted that their fossil remains of are fragmentary, so this assignment was only tentative.^[9] A 2021 study by Brian Andres also foundAlanqa as a thalassodromid, as well asArgentinadraco,Leptostomia, andXericeps within Thalassodromidae. He redefined the term Thalassodrominae for all taxa closer toThalassodromeus than toTupuxuara, which included all four of this genera.^[8] Other studies would not corroborate these results. In a 2022 study, Pêgas and colleagues re-evaluatedAerotitan and rejected its identity as a thalassodromid.^[21] Other studies have supported this conclusion.^[16][12] The 2022 study also reinterpreted the holotype ofAlanqa as a lower jaw as opposed to an upper one, and found it did not resemble those of thalassodromids. They concluded it to be more closely related to azhdarchids and named a new familyAlanqidae for it.^[21] A 2023 study by Roy Smith and all authors of the 2018 study would agree with this interpretation, rejectingAlanqa as a thalassodromid (though considering it an azhdarchid rather than an alanqid). They also expressed skepticism at the result ofLeptosomia andXericeps as thalassodromids, noting their fragmentary nature and concluding it was difficult to be certain of their position within Azhdarchoidea.^[22] Subsequent studies have placed these two genera andArgentinadraco in Alanqidae, Azhdarchidae, orChaoyangopteridae.^[12][16][23]

• Azhdarchoidea
• Reptile families
• Albian reptiles
• Reptiles of Brazil

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• Short description is different from Wikidata
• Articles with 'species' microformats
• Taxonbars with multiple manual Wikidata items