"Rectamphibius tridactylus" — A Provisional Classification of the J-Type Tridactyl Specimens

Title:Rectamphibius tridactylus gen. et sp. nov. — Anatomical, Radiographic, and Comparative Evidence Supporting Amphibian Classification of the J-Type Specimens Description (Abstract):The J-Type tridactyl specimens from southern Peru, once dismissed as fabrications, exhibit a consistent suite of amphibian skeletal and soft-tissue features confirmed through radiographic and computed tomography imaging. This study integrates morphological analysis, comparative anatomy, and independent AI-assisted classification to reassess their biological placement.The results demonstrate fused limb bones (radioulna and tibiofibula), tridactyl extremities, circular ribs lacking a sternum, porous desiccated integument, and flexible pelvic-spinal articulation—traits convergent with derived anuran amphibians rather than reptiles or mammals.The designation Rectamphibius tridactylus gen. et sp. nov. is proposed as a provisional classification reflecting these distinct anatomical and functional features. The findings underscore the need for transparent access to the physical specimens, amphibian-specific genetic testing, and multidisciplinary review to clarify evolutionary context.This dataset includes figures, CT interpretations, and comparative anatomical documentation supporting the reinterpretation of the J-Type as an anuran-grade amphibian. Keywords:Rectamphibius tridactylus; J-Type specimens; amphibian morphology; tridactyl anatomy; Nazca region; radiographic analysis; anuran evolution; pelvic-spinal dynamics; oviparity; CT scan; semi-aquatic adaptation; comparative anatomy; morphological classification. License:CC BY 4.0 (Attribution International) Authors:Juan F. Culajay Jr. — Ecity Solutions LLC Publication Type:Preprint / Research Data with Figures and Radiographs Funding (optional):Independent research; no formal grant support declared. 📊 Figure Legends Figure 1. Rib Count and Thoracic Structure of Rectamphibius tridactylus.Radiographic image of two J-Type specimens showing 10 pairs of circular ribs, including two floating pairs. Numbering highlights rib sequence from superior (1) to inferior (10). This configuration combines primitive rib retention with derived anuran limb fusions, supporting placement on the anuran stem lineage. Figure 2. Comparative radiographs of pelvic orientation in Rectamphibius tridactylus.Lateral and ventral radiographs depicting the flexible, non-fused pelvis and posterior (kyphotic) spinal curvature. The configuration demonstrates potential for vertical and horizontal pelvic reorientation associated with semi-aquatic locomotion and gravid posture. Figure 3. Radiograph of abdominal cavity.A J-Type specimen displays three dense, oval structures interpreted as soft-shelled, egg-like formations. While not definitive proof of oviparity, their consistent positioning and concentric density patterns indicate possible reproductive retention prior to deposition. Figure 4. 3D reconstruction of J-Type organism.Annotated external model showing cranial, axial, and appendicular traits. Labels correspond to key features, including fused radioulna, tridactyl extremities, and circular thoracic configuration. Figure 5. Cranial and anterior thoracic morphology of the J-Type specimen (Rectamphibius tridactylus).Cranial rendering and CT overlay reveal a beak-like oral aperture composed of two hinged bony plates, a prominent metopic crest, large almond-shaped orbits, and absence of visible external ear structures. The cervical region appears retractile, suggesting adaptive shortening within the torso. Figure 6. Hypothetical phylogenetic placement within Amphibia.Simplified cladogram showing Rectamphibius tridactylus positioned between early proto-anurans (Triadobatrachus) and crown-group Anura, retaining primitive rib count but displaying derived limb fusions and tridactyly.