Huizachal Canyon (general): Pliensbachian, Mexico
collected by J. Clark 1982-

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Tritylodontidae
1 specimen
IGM 3492 (holotype), skull
Mammalia - Eutriconodonta - Gobiconodontidae
Clark et al. 1994 2 specimens
"taxon C"
Montellano et al. 2008
IGM 6619, fragment of maxilla (holotype)
Reptilia
Rivera-Sylva and Carpenter 2014
"inferred from fragments of large bones"
Clark et al. 1994
Isolated teeth
Reynoso 2006
Skull fragment
? Metasuchia indet. Benton and Clark 1988
Clark et al. 1994
"new species"; IGM 3498 & additional specimens. Partial skulls and postcranial skeletons
Reptilia - Rhynchocephalia - Sphenodontidae
Reynoso 1996 26 specimens
IGM 6652, dentary. IGM 6653-6660, upper and lower jaws, and 16 incomplete lower jaws
see common names

Geography
Country:Mexico State/province:Tamaulipas
Coordinates: 26.6° North, 99.5° West (view map)
Paleocoordinates:
Basis of coordinate:based on nearby landmark
Altitude:146 meters
Geographic resolution:local area
Time
Period: Jurassic Epoch: Early Jurassic
Stage: Pliensbachian 10 m.y. bin: Jurassic 2
*Period:Early/Lower Jurassic - Middle Jurassic
*International age/stage:Hettangian - Callovian
Key time interval: Pliensbachian
Age range of interval: 192.9 - 184.2 m.y. ago
Age estimate: maximum 189 ± 0.2 Ma (U/Pb)
* legacy (obsolete) database fields
Stratigraphy
Geological group:Huizachal Formation:La Boca
Stratigraphic resolution:member
Stratigraphy comments: lower part of the La Boca Formation; originally dated as Middle Jurassic, but U-Pb isotopic data from zircon in a volcaniclastic rock from the lowest part of the formation yields an age of 189 plus/minus 0.2 Ma. The fossil-bearing sedimentary rocks are above this unit and conformable with it (see Montellano et al. 2008).
Lithology and environment
Primary lithology:volcaniclastic lithified siltstone
Includes fossils?Y
Environment:"floodplain"
Geology comments: "deposited as a subaerial, waterlain debris flow"
Taphonomy
Modes of preservation:body
Size of fossils:macrofossils,mesofossils
Preservation of anatomical detail:medium
Articulated whole bodies:some
Associated major elements:some
Disassociated major elements:none
Collection methods and comments
Collection methods:surface (float),surface (in situ),mechanical,field collection
Reason for describing collection:taxonomic analysis
Collectors:J. Clark Collection dates:1982-
Collection method comments: IGM: Instituto de Geologia, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, Mexico
Metadata
Database number:28212
Authorizer:M. Carrano, R. Butler, P. Mannion Enterer:M. Carrano, J. Tennant, R. Butler
Modifier:M. Carrano Research group:vertebrate
Created:2003-01-30 08:13:58 Last modified:2025-02-22 15:12:02
Access level:the public Released:2003-01-30 08:13:58
Creative Commons license:CC0
Reference information

Primary reference:
7714. J. M. Clark and J. A. Hopson. 1985. Distinctive mammal-like reptile from Mexico and its bearing on the phylogeny of the Tritylodontidae. Nature 315(6018):398-400 [M. Carrano/M. Carrano/M. Carrano]

Secondary references:

82052 G. Carbot-Chanona. 2014. Overview of Mesozoic crocodyliforms from Mexico. In H. E. Rivera-Sylva, K. Carpenter, & E. Frey (eds.), Dinosaurs and Other Reptiles from the Mesozoic of Mexico 110-125 [M. Carrano/M. Carrano]
43804 J. M. Clark and R. Hernandez. 1994. A new burrowing diapsid from the Jurassic La Boca Formation of Tamaulipas, Mexico. Journal of Vertebrate Paleontology 14(2):180-195 [R. Butler/R. Butler]
77135% 3640J. M. Clark, J. A. Hopson, R. Hernandez, D. E. Fastovsky, and M. Montellano. 1997. A primitive pterosaur from the Jurassic of Mexico and its implications for pterosaur foot posture. Journal of Vertebrate Paleontology 17(3, suppl.):38A-39A [M. Carrano/M. Carrano/J. Alroy]
7715 J. M. Clark, J. A. Hopson, R. R. Hernández, D. E. Fastovsky, and M. Montellano. 1998. Foot posture in a primitive pterosaur. Nature 391:886-889 [M. Carrano/M. Carrano/J. Alroy]
43803 J. M. Clark, M. Montellano, J. A. Hopson, R. Hernandez, and D. E. Fastovsky. 1994. An Early or Middle Jurassic tetrapod assemblage from the La Boca Formation, northeastern Mexico. In N. C. Fraser, H.-D. Sues (eds.), In the Shadow of the Dinosaurs: Early Mesozoic Tetrapods 295-302 [R. Butler/R. Butler/R. Butler]
81945 J. R. Guzmán-Gutiérrez and H. E. Rivera-Sylva. 2014. History of the discoveries of dinosaurs and Mesozoic reptiles in Mexico. In H. E. Rivera-Sylva, K. Carpenter, & E. Frey (eds.), Dinosaurs and Other Reptiles from the Mesozoic of Mexico 1-12 [M. Carrano/M. Carrano]
61988 R. Hernández-Rivera. 1997. Mexican dinosaurs. In P. J. Currie & K. Padian (ed.), Encyclopedia of Dinosaurs 433-437 [M. Carrano/M. Carrano]
43805 M. Montellano, J. A. Hopson, and J. M. Clark. 2008. Late Early Jurassic mammaliaforms from Huizachal Canyon, Tamaulipas, Mexico. Journal of Vertebrate Paleontology 28(4):1130-1143 [R. Butler/R. Butler]
36121 R. C. Munter and J. M. Clark. 2006. Theropod dinosaurs from the Early Jurassic of Huizachal Canyon, Mexico. In M. T. Carrano, T. J. Gaudin, R. W. Blob, J. R. Wible (eds.), Amniote paleobiology: perspectives on the evolution of mammals, birds, and reptiles. University of Chicago Press, Chicago 53-75 [O. Rauhut/O. Rauhut]
82053 V. H. Reynoso and J. A. Cruz. 2014. Mesozoic lepidosauromorphs of Mexico: a review and discussion of taxonomic assignments. In H. E. Rivera-Sylva, K. Carpenter, & E. Frey (eds.), Dinosaurs and Other Reptiles from the Mesozoic of Mexico 44-78 [M. Carrano/M. Carrano]
7927 V.-H. Reynoso. 1996. A Middle Jurassic Sphenodon-like sphenodontian (Diapsida: Lepidosauria) from Huizachal Canyon, Tamaulipas, Mexico. Journal of Vertebrate Paleontology 16(2):210-221 [M. Carrano/M. Carrano/R. Butler]
46663 V.-H. Reynoso. 2006. Research on fossil amphibians and reptiles in Mexico, from 1869 to early 2004 (including marine forms but excluding pterosaurs, dinosaurs, and obviously, birds). In F. J. Vega, T. G. Nyborg, M. Del Carmen Perrilliat, M. Montellano-Ballesteros, S. R. S. Cevallos-Ferriz, S. A. Quiroz-Barroso (eds.), Studies on Mexican Paleontology 24:209-231 [P. Mannion/J. Tennant]
35196 V.-H. Reynoso and J. M. Clark. 1998. A dwarf sphenodontian from the Jurassic La Boca Formation of Tamaulipas, Mexico. Journal of Vertebrate Paleontology 18:333-339 [R. Butler/R. Butler]
82004 H. E. Rivera-Sylva and K. Carpenter. 2014. Mexican saurischian dinosaurs. In H. E. Rivera-Sylva, K. Carpenter, & E. Frey (eds.), Dinosaurs and Other Reptiles from the Mesozoic of Mexico 143-155 [M. Carrano/M. Carrano]
30640ETE H. E. Rivera-Sylva, R. Rodríguez-de la Rosa, and J. A. Ortiz-Mendieta. 2006. A review of the dinosaurian record from Mexico. In editors: F. J. Vega, T. G. Nyborg, M. d. C. Perrilliat, M. Montellano-Ballestero (eds.), Studies on Mexican Paleontology; Topics in Geobiology 24:233-248 [M. Carrano/M. Carrano]