Paludocyon (from Latin: paludes, 'swamp' and Greek: κύων, cyon, 'dog') is an extinct genus of amphicyonids, a group known colloquially as "bear-dogs". Its type species, P. bohemicus, has been known since the 19th Century, but its affinities had long been in doubt, having variously been assigned to a number of other genera. It was only established as a distinct genus in the 2020s, after a review of Czech amphicyonids, which was followed by the reassigment of several other taxa originally described in 1950 to Paludocyon. Its members include medium-sized amphicyonids, that were distributed throughout Europe during the Early Miocene, with fossils being found in Czechia, Germany, France, and Spain.
Taxonomy Fossils, which includes several teeth, as well as a mandible, belonging to the type species of this genus were discovered at the site of Tuchořice, in the Czech Republic, during the 19th Century, and originally assigned to the species Amphicyon intermedius (now known as Crassidia intermedia) by Suess, following a conversation with Herrmann von Meyer.
In 1899, Schlosser noted that the remains, which included numerous premolars and molars belonging to a single individual, represented a distinct species, which he named Pseudocyon bohemicus. On the basis of drawings of Suess, he argued that the unique cusps of the molars clearly differentiated it from the known species of Amphicyon, and that the same species was also present at the locality Weisenau, near Mainz. Two years later, he reassigned this species back to the genus Amphicyon, as A. bohemicus, because being able to view the original material made him notice several distinctions. In the following decades, its taxonomic position remained disputed, with Kuss arguing in 1965 that it was a subspecies of Amphicyon steinheimensis, with A. s. bohemicus being the ancestor of the nominal subspecies A. s. steinheimensis, while assigning a molar as new lectotype. He corrected what he viewed as mistakes of Schlosser, such as a too Pseudocyon-like reconstruction of the second lower molar, arguing that Schlosser did not render the understanding of this species a favor with his dental combinations and reconstructions. Kuss furthermore argued that A. s. bohemicus was identitical with the species described by Dehm as A. dietrichi fifteen years earlier. The assignment to A. steinheimensis was not followed by later authors, though Ginsburg saw them as closely related members of one lineage, for which he subgenus Heizmannocyon. Peigne et al. viewed the latter as synonymous with Cynelos. Therefore, they renamed the species from Czechia Cynelos bohemicus. Finally, in a 2021 revision of Tuchořice amphicyonids, Morales et al. erected the new genus Paludocyon, named after the swampy environment of Tuchořice, with P. bohemicus serving as its type species. A study by the same lead authors in 2026 described the species P. moyasolai from Spain, while also reassigning three species described by Dehm to this genus.
Species P. acutidens
This species was originally described by Dehm as Amphicyon acutidens in 1950, with parts of the jaws, and associated teeth, serving as the holotype. It was discovered at the early Miocene locality of Wintershof-West, in Bavaria. Dehm established two more species, A. dietrichi and A. helbingi, from the locality in the same publication. He noted that A. acutidens overlapped with A. helbingi in terms of size, but while he commented on the great similarity and close relationship between the two, he viewed them as distinct. According to him, A. acutidens had a 'sharper' dentition (from which the species name derives), and the reduction of the M² compared to the M¹ has progressed even further than among A. helbingi, while the latter has a longer p₂ and a bigger m₂. This was not followed by many subsequent authors, with acutidens instead being seen as a junior synonym to helbingi.
P. bohemicus
Established as the type species of the genus in 2021, P. bohemicus had a difficult taxonomic history, with previous authors having considered it a species of Amphicyon, Cynelos, Heizmannocyon or Pseudocyon. It was originally discovered at the Czech site Tuchořice during the 19th century, and is known from several remains, including a mandible and various teeth. The species has also been reported from the Halamagai Formation in China, and at Thenay in France, which would extend its temporal range to MN 5, though these have been dismissed by Morales et al., who rather suggest these remains are closer to P. helbingi and Heizmannocyon, respectively.P. dietrichi
Paludocyon dietrichi is one of the species from Wintershof-West described by Dehm, who originally attributed it to the genus Amphicyon. The holotype is a partial lower jaw, while another jaw fragment is known from the same locality, as is a partial snout. He described it as a large species, comparable in size to Crassidia. The species name was erected in honor of Wilhelm Otto Dietrich. Kuss viewed the species as junior synonym to P. bohemicus, in which he was followed by a number of later authors. Morales et al. challenged this in 2021, reviving P. dietrichi as distinct species, though they viewed it as more closely associated with Pseudocyon. However, a 2026 study by the same lead authors, which assigned dietrichi to Paludocyon, recovered P. dietrichi and P. bohemicus as each other's closest relatives.P. helbingi
As two other members of the genus, P. helbingi was originally described by Dehm as a new species of Amphicyon discovered at Wintershof-West. Its name is a tribute to Hans Helbings. The holotype is a fragmentary jaw, though numerous other fragments and numerous teeth have also been discovered, which includes those of juveniles as well. As the teeth show remarkable differences in size, with the lengths of the first lower molars ranging from 19.8 to 27.1 mm, Dehm was at first skeptical should really be treated as a singular species. For Kuss, this taxon was a subspecies of Cynelos lemanensis, with acutidens being its synonym. Later authors followed Kuss in synonymizing helbingi and acutidens, though they treated the former as a distinct species, rather than a mere subspecies. P. helbingi is the oldest member of the genus in Europe, and has been found across localities in Germany, Spain, and France, though the assignment of many of these is tentative. It is securely known from sites dating to MN 3 and MN 4 (with the youngest occurrences at Buñol and Erkertshofen 2), though it has also been reported from Selles-sur-Cher, which would extend its range to late MN 2. These remains have alternatively been assigned to Cynelos lemanensis, and Hunt has suggested that they represent a traditional form between the two species. Remains with affinities to P. helbingi have been reported in the Chinese Halamagai Formation, which is somewhat younger, correlating to the MN 5.
P. moyasolai
Discovered at the site of els Casot in Catalonia, part of the Vallès-Penedès Basin, P. moyasolai was described in 2026. The holotype is an almost complete, but crushed, skull, with the snout being badly preserved. An isolated lower molar, likely belonging to the same individual, has also been discovered. It differs from other members of the genus in the shape of its upper molars, with the M¹ being broader compared to the M². The third molar is more well developed, and has well-defined anterior cusps. Compared to P. bohemicus, the fourth premolar is shorter. Its name honors Salvador Moyà-Solà, in honor of his role in the development of European paleomastology.
Phylogeny and evolutionary relationships The close relationship between members of this genus and Cynelos has long been recognized. Already Dehm suggested that P. helbingi, closely affiliated with P. dietrichi, is a descendant of Cynelos lemanensis, in which he was followed by a variety of other authors, including Kuss and Ginsburg. The close relationship was supported by Hunt, who suggested that the fossils from Selles-sur-Cher represented a transitional form between the two species. Peigne & Heizmann considered this close relationship to be less obvious, noting the clear dental differences between the two. It has also been proposed that P. bohemicus descends from C. lemanensis, though Kuss is skeptical of the idea, as he considered the two taxa to be coeval. However, he did consider it ancestral to Heizmannocyon steinheimensis (in his classification, Amphicyon steinheimensis steinheimensis), an idea that was followed by Ginsburg.The traditional classification system was increasingly challenged by Morales et al., who considered the genus Cynelos, with species described across Europe, Asia, Africa, and North America, to have been a wastebasket-taxon, with many of its supposed species showing remarkable difference to the type species C. lemanensis. They resurrected or established a number of genera previously viewed as part of Cynelos (including Paludocyon), and suggested that it was paraphyletic. According to them, both Cynelos and Paludocyon are members of the tribe Amphicyonini, and their cladistic analysis supports a clade that includes both genera, while excluding Dehmicyon, Absonodaphoenus, Pseudocyonopsis, and Daphoenodon. Within this clade, the species of Paludocyon form a group without the species attributed to Cynelos. For the latter, the North American species are recovered as closer to Paludocyon than to C. lemanensis, though they note that any divergence must have taken place in the late Oligocene or earliest Miocene, and suggest a separate evolutionary history of North American Cynelos species.
Below is a cladogram depicting the phylogenetic relationships of Paludocyon, following Morales et al. (2026).
Description
Paludocyon was generally a medium-sized genus of amphicyonids. The basilar skull-length of P. dietrichi has been reconstructed at ~32 cm, much larger than in the American Cynelos malasi (~20 to 22 cm). The body mass of female P. helbingi has been estimated at 60 kg, with males being larger at 86 kg. It is slightly larger than Cynelos lemanensis on average. Another study also estimated P. bohemicus at 86 kg. Dehm noted that P. dietrichi was a large species, comparable in size to Crassidia.
The diagnostic features of Paludocyon are traits of its dentition, specifically, it is characterized by its small p₄, with a wide talonid, a robust m1, and shortened m₂ in the lower jaw. The third molars are reduced in both upper and lower jaw. Compared to Cynelos, the posterior molars (M²/M³ and m₂/m₃) are less developed than the first molars. Its crushing dentition is narrower than that of Amphicyon major, and it differs from that genus in the presence of more primitive dental characters, a more compressed snout, narrower m₁ and m₂ as well as generally smaller carnassials and molars. Its lower premolars are reduced compared to Cynelos, Amphicyon, and Heizmannocyon. From the latter it also differs through wider diastemas between its premolars, while its M¹/M² and m₁ are more slender, though the lower molars are more robust than in Pseudocyon. Overall, the trend in Paludocyon is a moderate increase in size of the crushing teeth, the reduced lower premolars, and the widened talonid of the m₁. The upper premolars of P. moyasolai increase in size the farther back they go. Dehm described the jaws of P. dietrichi as considerably more bear-like than those of Crassidia intermedia. The dentition of Paludocyon is relatively hypercarnivorous.
Paleoecology