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Pseudogavialis
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Pseudogavialis
Pseudogavialis is an extinct genus of gavialoid from the Oligocene to Miocene Laki and Bugti Hills of Pakistan (probably the Chitarwata and Chinji Formations). Pseudogavialis was originally named by Richard Lydekker as "Gharialis" curvirostris in 1886, a misspelling of Gavialis, the genus that contains today's Indian gharial. Eventually it was recognized that the material belonged to a distinct genus, which was named Pseudogavialis in 2025. Like the closely related modern Indian gharial, Pseudogavialis had long and slender jaws with numerous interlocking teeth. It might have reached a length of up to 6–7 metres (20–23 ft).
Remains of fossil gavialoids have been known from Pakistan since around the late 19th century, with several being named as new species related to the modern gharial. Among these was "Gharialis" curvirostris, which was discovered during the early 19th century (no later than 1846) and was described by Richard Lydekker alongside "Gharialis" pachyrhynchus in 1886. "Gharialis" curvirostris was established on the basis of two pieces of the skull from the Laki Hills of Sindh, one preserving the very tip of the snout and the other the region just before the eyes, which clearly represent a single individual. Lydekker also describes additional skull remains, but unlike the holotype these weren't figured. In 1908 Guy Ellcock Pilgrim also reported to have found material of "G." curvirostris, reportedly from the Bugti Hills. While Pilgrim would eventually come to assign these fossils to their own taxon, "G." breviceps, the same 1912 paper to coin said name also makes mention of material from the Gaj of Kumbi, also located within the Bugti Hills. These three specimen were described as "Garialis" curvirostis var. gajensis in 1912, as Pilgrim believed them to represent a variant of Lydekker's species. The material that makes up "G." curvirostris" var. gajensis was also relatively complete, preserving almost the entire snout, elements of the posterior skull and even parts of the lower jaw. The next material attributed to this species was published in 2005 by Piras and Kotsakis, this time under the name "Gavialis" curvirostris. Both Richard Swann Lull and Piras & Kotsakis state that the material comes from the Chinji Formation. However Jeremy E. Martin later argued that the latter left it ambiguous whether or not they meant the Chinji Formation or simply a locality of the same name.
With a plethora of species and specimen being present in literature, Jeremy E. Martin published a study reviewing these various forms in 2019. Martin suggests in this study that both "Gavialis" curvirostris and "Gavialis" curvirostris var. gajensis could very well be the same species. The paper furthermore hypothesizes that these forms could either be synonyms of Rhamphosuchus or that they are a new species of tomistomine. Regardless of the outcome, the paper is clear in the fact that the material does not belong to the modern genus Gavialis, with the same being the case for much of the material from Neogene Pakistan.
Another review and revision would eventually be published in 2025, authored by Erwan Courville and colleagues and dealing with the taxonomy of not only "Gavialis" curvirostris but also "Gavialis" pachyrhynchus, Gavialis breviceps and Rhamphosuchus crassidens. The study concludes that "Gavialis" curvirostris is distinct enough to be placed in its own genus, which the team names Pseudogavialis based on Lydekkers material. However, the case of Pilgrim's variant is more complex. Following the study, the mandible of "G." curvirostris var. gajensis does belong to Pseudogavialis, however, the rostrum described by Pilgrim appears to represent an intermediate between Pseudogavialis and "G." pachyrhynchus (dubbed Rhamphosuchus pachyrhynchus by the team) and is therefore tentatively identified as a new species of Rhamphosuchus. Pilgrim's posterior skull on the other hand cannot be assigned to any specific taxon beyond having belonged to a Crocodilian. In addition to reviewing already known material, Courville and colleagues also describe additional material collected during the 1990s from the Bugti Hills, specifically the Aquitanian Chitarwata Formation.
The name Pseudogavialis was chosen due to the animals broad resemblance to modern gharials, despite not being part of the genus as has been historically proposed.
Pseudogavialis was a large crocodilian similar in size to today's Indian gharial, reaching lengths of around 6–7 metres (20–23 ft). It can easily be distinguished from the contemporary Rhamphosuchus pachyrhynchus and today's gharials by the shape and proportions of the premaxillae, which come together to form the tip of the snout. In Pseudogavialis, they are comparable in width to the elongated maxillae that form the majority of the rostrum, with outer edges that are described as rounded. By contrast, in modern gharials and in Rhamphosuchus pachyrhynchus the premaxillae are laterally expanded, meaning they widen in a way that gives the tip of the snout a much more distinct shape. However, the expansion of the premaxillae could be related to the presence of what is known as a ghara, a soft tissue structure present in adult male Indian gharials. Therefore, this might be a sexually dimorphic feature, with the expansion being present in males and absent in females. Aside from the fact that the premaxillae are not expanded, the fact that the premaxillary teeth of Pseudogavialis are much more widely spaced than those of Rhamphosuchus means that the premaxillae also appear much more elongated by comparison.
The large naris is entirely enclosed by the premaxillae and trapezoid in shape, another feature quite different from Rhamphosuchus which had a circular narial opening. The back of this opening is surrounded by a gentle ridge. Pseudogavialis appears to have lacked the depressions before and behind the nares that are seen in Rhamphosuchus crassidens and the Indian gharial, however, much like the expansion of the premaxillae this feature could tie into the presence or absence of a ghara and therefore differ between sexes. Behind the naris the two premaxillae contact each other along the midline of the skull, forming two highly elongated processes that extend as far back as the seventh maxillary teeth along a V-shaped contact with the maxillae to either side. Towards their posterior-most point, the premaxillary processes actually come into contact with the paired nasal bones. Similarly, the premaxillae contact the nasals in both the contemporary species of Rhamphosuchus and today's false gharial (Tomistoma), while the two bones don't touch each other in Rhamphosuchus crassidens and the modern Indian gharial.
The remainder of the rostrum is mostly formed by the maxillae, which stretch from just behind the final premaxillary tooth all the way to the posterior part of the skull. As noted by Courville and colleagues, the outer edges of the maxillae run almost parallel to each other like in Indian gharials, which despite the fragmentary material indicates that the snout of Pseudogavialis was quite elongated.
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Pseudogavialis
Pseudogavialis is an extinct genus of gavialoid from the Oligocene to Miocene Laki and Bugti Hills of Pakistan (probably the Chitarwata and Chinji Formations). Pseudogavialis was originally named by Richard Lydekker as "Gharialis" curvirostris in 1886, a misspelling of Gavialis, the genus that contains today's Indian gharial. Eventually it was recognized that the material belonged to a distinct genus, which was named Pseudogavialis in 2025. Like the closely related modern Indian gharial, Pseudogavialis had long and slender jaws with numerous interlocking teeth. It might have reached a length of up to 6–7 metres (20–23 ft).
Remains of fossil gavialoids have been known from Pakistan since around the late 19th century, with several being named as new species related to the modern gharial. Among these was "Gharialis" curvirostris, which was discovered during the early 19th century (no later than 1846) and was described by Richard Lydekker alongside "Gharialis" pachyrhynchus in 1886. "Gharialis" curvirostris was established on the basis of two pieces of the skull from the Laki Hills of Sindh, one preserving the very tip of the snout and the other the region just before the eyes, which clearly represent a single individual. Lydekker also describes additional skull remains, but unlike the holotype these weren't figured. In 1908 Guy Ellcock Pilgrim also reported to have found material of "G." curvirostris, reportedly from the Bugti Hills. While Pilgrim would eventually come to assign these fossils to their own taxon, "G." breviceps, the same 1912 paper to coin said name also makes mention of material from the Gaj of Kumbi, also located within the Bugti Hills. These three specimen were described as "Garialis" curvirostis var. gajensis in 1912, as Pilgrim believed them to represent a variant of Lydekker's species. The material that makes up "G." curvirostris" var. gajensis was also relatively complete, preserving almost the entire snout, elements of the posterior skull and even parts of the lower jaw. The next material attributed to this species was published in 2005 by Piras and Kotsakis, this time under the name "Gavialis" curvirostris. Both Richard Swann Lull and Piras & Kotsakis state that the material comes from the Chinji Formation. However Jeremy E. Martin later argued that the latter left it ambiguous whether or not they meant the Chinji Formation or simply a locality of the same name.
With a plethora of species and specimen being present in literature, Jeremy E. Martin published a study reviewing these various forms in 2019. Martin suggests in this study that both "Gavialis" curvirostris and "Gavialis" curvirostris var. gajensis could very well be the same species. The paper furthermore hypothesizes that these forms could either be synonyms of Rhamphosuchus or that they are a new species of tomistomine. Regardless of the outcome, the paper is clear in the fact that the material does not belong to the modern genus Gavialis, with the same being the case for much of the material from Neogene Pakistan.
Another review and revision would eventually be published in 2025, authored by Erwan Courville and colleagues and dealing with the taxonomy of not only "Gavialis" curvirostris but also "Gavialis" pachyrhynchus, Gavialis breviceps and Rhamphosuchus crassidens. The study concludes that "Gavialis" curvirostris is distinct enough to be placed in its own genus, which the team names Pseudogavialis based on Lydekkers material. However, the case of Pilgrim's variant is more complex. Following the study, the mandible of "G." curvirostris var. gajensis does belong to Pseudogavialis, however, the rostrum described by Pilgrim appears to represent an intermediate between Pseudogavialis and "G." pachyrhynchus (dubbed Rhamphosuchus pachyrhynchus by the team) and is therefore tentatively identified as a new species of Rhamphosuchus. Pilgrim's posterior skull on the other hand cannot be assigned to any specific taxon beyond having belonged to a Crocodilian. In addition to reviewing already known material, Courville and colleagues also describe additional material collected during the 1990s from the Bugti Hills, specifically the Aquitanian Chitarwata Formation.
The name Pseudogavialis was chosen due to the animals broad resemblance to modern gharials, despite not being part of the genus as has been historically proposed.
Pseudogavialis was a large crocodilian similar in size to today's Indian gharial, reaching lengths of around 6–7 metres (20–23 ft). It can easily be distinguished from the contemporary Rhamphosuchus pachyrhynchus and today's gharials by the shape and proportions of the premaxillae, which come together to form the tip of the snout. In Pseudogavialis, they are comparable in width to the elongated maxillae that form the majority of the rostrum, with outer edges that are described as rounded. By contrast, in modern gharials and in Rhamphosuchus pachyrhynchus the premaxillae are laterally expanded, meaning they widen in a way that gives the tip of the snout a much more distinct shape. However, the expansion of the premaxillae could be related to the presence of what is known as a ghara, a soft tissue structure present in adult male Indian gharials. Therefore, this might be a sexually dimorphic feature, with the expansion being present in males and absent in females. Aside from the fact that the premaxillae are not expanded, the fact that the premaxillary teeth of Pseudogavialis are much more widely spaced than those of Rhamphosuchus means that the premaxillae also appear much more elongated by comparison.
The large naris is entirely enclosed by the premaxillae and trapezoid in shape, another feature quite different from Rhamphosuchus which had a circular narial opening. The back of this opening is surrounded by a gentle ridge. Pseudogavialis appears to have lacked the depressions before and behind the nares that are seen in Rhamphosuchus crassidens and the Indian gharial, however, much like the expansion of the premaxillae this feature could tie into the presence or absence of a ghara and therefore differ between sexes. Behind the naris the two premaxillae contact each other along the midline of the skull, forming two highly elongated processes that extend as far back as the seventh maxillary teeth along a V-shaped contact with the maxillae to either side. Towards their posterior-most point, the premaxillary processes actually come into contact with the paired nasal bones. Similarly, the premaxillae contact the nasals in both the contemporary species of Rhamphosuchus and today's false gharial (Tomistoma), while the two bones don't touch each other in Rhamphosuchus crassidens and the modern Indian gharial.
The remainder of the rostrum is mostly formed by the maxillae, which stretch from just behind the final premaxillary tooth all the way to the posterior part of the skull. As noted by Courville and colleagues, the outer edges of the maxillae run almost parallel to each other like in Indian gharials, which despite the fragmentary material indicates that the snout of Pseudogavialis was quite elongated.
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