‘Mystery big cats’ in the Peruvian Amazon: morphometrics solve a cryptozoological mystery

Darren Naish1*, Manabu Sakamoto2, Peter Hocking3, Gustavo Sanchez4

1 Ocean and Earth Science, National Oceanography Centre, Southampton, University of Southampton, SouthamptonSO14 3ZH, UK

2School of Earth Sciences, University of Bristol, Bristol, BS8 1RJ, UK

3Natural History Museum of the University of San Marcus, Lima, Peru

4Fundación Neotrópico, La Laguna, 38208, Tenerife, Canary Islands, Spain

* Author and address for correspondence ()

Data on whereabouts of specimens

The original specimens are retained in the collections of the Natural History Museum of the National Higher University of San Marcos, Lima, Peru, where they are accessioned as MHN 9397 (‘anomalous jaguar’) and MHN 8736 (‘Peruvian tiger’). High quality casts were created by making plaster molds, then by making acrylic casts from the molds. It is these replicas that were used for our study. The casts are housed at the Fundación Neotrópico, La Laguna, Tenerife, Canary Islands where they are accessioned as CF-0022 (‘anomalous jaguar’) and CF-0023 (‘Peruvian tiger’).

Craniomandibular measurements recorded from both skulls. The 36 cranial and 13 mandibular measurements are illustrated on the replica skull and mandible of the ‘Peruvian tiger’ (CF-0023). Values were recorded using a digital caliper.Numbers as in Table 1.

TABLE 1. Cranial and mandibular measurements of the two Peruvian cats in mm.*, mean value of left and right measurements.

Variable‘Anomalous jaguar’‘Peruvian tiger’

  1. LSkT250218
  2. LFr7667
  3. LPa-Oc10787
  4. Lface10488
  5. Wiof6458
  6. Wo4439
  7. WPOC4343
  8. WPOP6157
  9. WBC7675
  10. Wsn6859
  11. WC1s7058
  12. WNA3128
  13. LN5544
  14. LNT6554
  15. WMFS2323
  16. LCdBs223193
  17. LBsCr6859
  18. WIC1s3631
  19. WI3s-I3s3025
  20. LC1sP3s1111.5
  21. Wsk162144
  22. WP4s-P4s8880
  23. Wpal9786
  24. Lpal10491
  25. LPMMX6252
  26. WPN2020
  27. WPN.ant2221
  28. WMP10192
  29. WPocP7768
  30. dAB.ant2525
  31. dAB.post4539
  32. WOC4847
  33. HOC2118
  34. WFM2526
  35. WFMV2623
  36. LP4s*28.725.2
  37. LSym5548
  38. LMand*159141
  39. LDiast*13.516
  40. Lm1*20.9518.35
  41. DMdM1*3328
  42. DMdP4*31.526.5
  43. RT1*5544.5
  44. RT2*5547.5
  45. LCorProc*32.528.5
  46. RM1*34.532
  47. RM2*71.566
  48. DAngProc*1414
  49. DCond*12.512

Definitions of cranial and mandibular morphometric variables

  1. LSKT, greatest skull length
  2. LFr, frontal length
  3. LPa-Oc, parietal-occipital length
  4. Lface, facial length
  5. Wiof, snout width at the infraorbital foramen
  6. Wo, interorbital width
  7. WPOC, postorbital constriction width
  8. WPOP, postorbital process width
  9. WBC, braincase width
  10. Wsn, snout width at approximate midsnout
  11. WC1s, snout width at canines
  12. WNA, nasal aperture width
  13. LN, nasal length
  14. LNT, total nasal length
  15. WMFS, nasal width at maxillo-frontal suture
  16. LCdBs, condylo-basal length
  17. LBsCr, basicranial length
  18. WIC1s, intercanine distance
  19. WI3s-I3s, incisor arc width
  20. LC1sP3s, C1-P3 distance
  21. Wsk, skull width
  22. WP4s-P4s, palatal width at P4
  23. Wpal, palatal width posterior to P4
  24. Lpal, palatal length
  25. LPMMX, premaxillary-maxillary length along palatal midline
  26. WPN, postnarial passage width
  27. WPN.ant, postnarial passage width at the palatal margin
  28. WMP, mastoid process width
  29. WPocP, paroccipital process width
  30. dAB.ant, auditory bullae distance at the anterior margin
  31. dAB.post, auditory bullae distance at posterior margin
  32. WOC, occipital condylar width
  33. HOC, occipital condylar height
  34. WFM, foramen magnum width
  35. WFMV, foramen magnum width the ventral margin
  36. LP4s, P4 length
  37. LSym, mandibular symphysis length
  38. LMand, mandibular length
  39. LDiast, diastema length
  40. Lm1, m1 length
  41. DMdM1, mandibular depth at m1
  42. DMdP4, mandibular depth at p4
  43. RT1, temporal muscle lever arm1
  44. RT2, temporal muscle lever arm2
  45. LCorProc, antero-posterior coronoid process length
  46. RM1, masseter muscle lever arm1
  47. RM2, masseter muscle lever arm2
  48. DAngProc, angular process depth
  49. DCond, condylar depth