La Boca Formation Explained

La Boca Formation
Type:Geological formation
Period:Lower Jurassic
Age:Lower Pliensbachian-Latest Aalenian, [1]
Prilithology:Red sandstones, mudstones, and siltstones
Otherlithology:Pyroclastic volcanic rocks
Region:Tamaulipas
Unitof:Huizachal Group
Subunits:
  • Upper Part with Epiclastic Sedimentation
  • Lower Part with Pyroclastic sedimentation
Underlies:La Joya Formation
Overlies:Huizachal Formation
Thickness:<10 m

The La Boca Formation is a geological formation in Tamaulipas state, northeast Mexico. It was originally thought to date back to the Early Jurassic, concretely the Pliensbachian stage epoch of 193-184 Ma.[2] Later studies found that while the unit itself was likely deposited during the earliest Pliensbachian, as proven by zircon dating 189.0 ± 0.2 Ma, the local vulcanism (related to the aperture of the Atlantic Ocean and the several Rift Events) continued until the Bajocian.

However, the lower section of the fossil taxa deposited on the rocks above the La Boca Formation is likely of Late Pliensbachian-Lower Toarcian age, and the upper section of Late Toarcian-Late Aalenian age.[3]

Due to successions of Aalenian depositional systems on the upper layers of the Huizachal Canyon, has been delimited the formation to the Toarcian stage, being the regional equivalent of the Moroccan Azilal Formation.[4] Deposits of Late Triassic Age referred to this unit have been reclassified in a new formation, El Alamar Formation.[5] In North America, La Boca Formation was found to be a regional equivalent of the Eagle Mills redbeds of southern United States, the Todos Santos Formation of southern Mexico and the Barracas Group of the Sonora desert region.[6]

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Paleoenvironment

La Boca Formation is genetically related to the Nazas volcanic Arc of the same age (Pliensbachian-Aalenian, ~189.5–171.6 Ma), which was created when Mexico evolved in a convergent plate margin, with the Gulf of Mexico remaining as a restricted basin and a passive margin.[7] The influence of this arc is seen on the continental units such as Todos Santos Formation, which deposited volcanic materials in both nonmarine strata and marginal marine red beds of eastern Mexico.

La Boca Formation left its sediments on a basin formed between the Nazas Volcanic Arc center and the so-called Huizachal-Peregrina Anticlinorium, giving the basin layers whose origin is linked with braided river deposits with different flooding levels, channels fills, and channel belts filling valleys.[7]

In locations such as Aramberri, the development of fluvial channels and the flooding of surfaces was restricted due to the presence of flanking volcanic activity, as well the local Paleozoic basement highs.[7] In this outcrop the fluvial system evolved in several ways. Towards the north, it meanders from braided to ephemeral sandy, with the presence of common laminated sands sheets. The latter are likely a local indicator of unconfined flash floods across floodplains, with some sections recovering periods of desiccation thanks to the presence of mudcracks.

Towards the south, in localities such as El Olmo Canyon, the layers show gravelly braided rivers, oriented east-west, which then evolve into high-sinuosity single-thread meandering rivers.[7] Other southern localities, such as the Caballeros Canyon and Huizachal Canyon, have layers that record gravel-bed braided rivers over a floodplain with high-energy flows: an element recorded on the local stratigraphy as older layers which were highly degraded by the increased force of the younger flows. The rock fragments moved by the currents are bigger in upper layers. In the southernmost outcrop, in Miquihuana the sheet sands show greater flooding events than on any other location.[7]

In the main fossiliferous level of the Huizachal Canyon, in which more than 8000 specimens have been found, the preservation of delicate specimens such as Pterosaurs suggests an environment with little transportation and reworking. Yet the fossils were not buried in situ, as most of the smaller specimens show disarticulation.[8]

All data trends suggest a highly unusual debris-flow environment in which local fluvial alluvial bodies were not big enough to sustain large freshwater biota such as fishes, and most of the preserved specimens were fast-buried near the place of death.[8]

Fossil record

Ichnofossils

GenusSpeciesLocationMaterialTypeMade byNotesImages
Mermia
  • M. isp.
  • Valle de Huizachal
Locomotion traceDomichnia & Fodinichnia Densely looped grooves or ridges. Taxon linked with the major Early Jurassic flooding of the Huizachal Valley, developed locally mostly on a gravel-bed braided fluvial style with paleocurrents oriented west-northwest
Scoyenia
  • Valle de Huizachal
BurrowsDomichnia & Fodinichnia
  • Crustaceans
  • Worms
Burrow fossils in lacustrine or fluvial environments, probably made by arthropods

Synapsida

GenusSpeciesLocationStratigraphic positionAbundanceNotesImages
Bocaconodon[9] B. tamaulipensisJim's Joy, Huizachal Canyon Lower Part TeethA basal Mammaliaform
Bocatherium[10] [11] B. mexicanumHuizachal Canyon Lower PartIGM 3492, SkullA Tritylodontid
HuasteconodonH. wibleiHuizachal Canyon Lower PartTeethA Gobiconodont
VictoriaconodonV. inaequalisRene's Roost, Huizachal Canyon Lower Part TeethA Triconodontid
Unnamed Mammaliaforms (IGM 6622,IGM 6855, and IGM 6856)Indeterminate
  • Cementario, Huizachal Canyon
  • Casa de Fidencio, Huizachal Canyon
Lower Part IGM 6855, partial right dentary; IGM 6856, left dentary; IGM 6622, partial right dentary

Sphenodontia

GenusSpeciesLocationStratigraphic positionAbundanceNotesImages
Clevosaurusaff. C. sp.
  • Puente de Piedra
  • JMC 85-A
  • Rene Roost
  • Tierra Buena del Sur at Huizachal Canyon
Lower Part
  • IGM 6565, left lower jaw
  • IGM 6566, split left lower jaw
  • IGM 6567, broken lower jaw
  • IGM 6568, almost complete lower jaw
  • IGM 6569, split right? lower jaw
  • IGM 6570, split right? lower jaw.
A Sphenodontidae Rhynchocephalian of the family Clevosauridae.
Cynosphenodon[14] [15] C. huizachalensisHuizachal Canyon Lower Part
  • IGM 6652 Dental portion of the right dentary with a complete tooth row
  • IGM 6653, posterior right dentary
  • IGM 6654, anterior portion of a right maxilla
  • IGM 6655, middle portion of a right maxilla
  • IGM 6656, anterior part of a right dentary
  • IGM 6657, anterior portion of a right dentary
  • IGM 6658, symphysial region of a right dentary
  • IGM 6659, anterior part of a left dentary
  • IGM 6660, posterior part of a left dentary with coronoid process
A sphenodontine rhynchocephalian closely related to the living tuatara.[16]
Opisthiasaff. O. sp.
  • Rene's Roost and Puente de Piedra
  • Fidencio Hideway
  • Oeste de DNMS in Huizachal Canyon
Lower Part
  • IGM 6571, middle portion of a left lower jaw
  • IGM 6572, partial right lower lower jaw
  • IGM 6573, complete eroded right lower jaw
  • IGM 6574, left lower jaw
  • ?IGM 6748, partial right lower jaw
  • IGM 6749, partial left lower jaw
  • IGM 6750, almost complete right maxilla
  • IGM 6751, anterior portion of a right lower jaw
  • IGM 6752, partial right? lower jaw
  • IGM 6753, partial right lower jaw
  • IGM 6754, partial left? lower jaw
  • IGM 6755, very small partial left lower jaw
  • IGM 6756, partial left lower jaw
  • IGM 6757, partial right mandible, right maxilla, two incomplete vertebrae, a humerus epiphysis and some not recognized long bones
  • IGM 6758, partial right maxilla.
A Sphenodontidae Rhynchocephalian of the family Opisthodontia.
Sphenovipera[17] S. jimmysjoyiJim's Joy, Huizachal Canyon Lower Part IGM 6076, an almost complete right lower jaw with teeth A possible venomous Sphenodont
Zapatadon[18] Z. ejidoensisTierra Buena, western part of the Huizachal CanyonLower PartIGM 3497, crushed skull, missing part of the skull table and roofing bones A dwarf Sphenodont

Crocodylomorpha

GenusSpeciesLocationStratigraphic positionAbundanceNotesImages
MetasuchiaIndeterminateHuizachal Canyon Lower Part IGM 3498 & additional specimens. Partial skulls and postcranial skeletons Preliminary results suggest it may be a stem metasuchian.
Protosuchia[21] [22] IndeterminateHuizachal Canyon Lower Part Skull fragment A possible member of Protosuchia. Found to be sister taxon of Platyognathus hsui from the Lower Jurassic Lufeng Formation of Yunnan.

Dinosauria

GenusSpeciesLocationStratigraphic positionAbundanceNotesImages
CeratosauriaIndeterminateCasa de Fidencio, Huizachal Canyon Lower PartIGM 6625, craneal fragmentary elementsA possible basal ceratosaur related with the African Berberosaurus.
Heterodontosauridae[23] cf.H. sp.Huizachal Canyon Lower PartTeethAn Ornithischian of the family Heterodontosauridae.
"Megapnosaurus"[24] "M." mexicanum [25] Casa de Fidencio, Huizachal CanyonLower Part (IGM 6624) partial twelfth dorsal vertebra, partial thirteenth dorsal vertebra, partial synsacrum, incomplete fused pelvisAn indeterminate Coelophysoidean.
NeotheropodaIndeterminateHuizachal Canyon Lower PartIsolated teethSeveral morphotypes, maybe related with Coelophysoidea, Dilophosauridae or Tetanurae.
?SauropodomorphaIndeterminateRene's Roost, Huizachal Canyon Lower Part Large bone fragmentsA possible Basal Sauropodomorph.

Palynology

GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Araucariacites
  • A. cf. australis
  • La Escondida canyon
  • La Boca canyon
  • Lower Member
PollenA Pollen Grain, affinites with the family Araucariaceae inside Pinales. Conifer pollen from medium to large arboreal plants.
Exesipollenites
  • E. tumulus
  • La Escondida canyon
  • La Boca canyon
  • Lower Member
PollenA Pollen Grain, affinities with the Hirmeriellaceae in the Pinopsida.
Dapcodinium[26]
  • D. priscum
  • La Escondida canyon
  • La Boca canyon
  • Lower Member
CystsA Dinoflajellate of the family Rhaetogonyaulacaceae inside Gonyaulacales
Eucommiidites
  • E. troedssonii
  • La Escondida canyon
  • La Boca canyon
  • Lower Member
PollenA Pollen Grain, afinnities with Erdtmanithecales inside Spermatophytes.
Exesipollenites
  • E. tumulus
  • La Escondida canyon
  • La Boca canyon
  • Lower Member
PollenA Pollen Grain, affinities with the family Cupressaceae in the Pinopsida. Pollen that resembles that of extant genera such as the genus Actinostrobus and Austrocedrus, probably derived from dry environments.
Dictyophillidites
  • D. sp. 1
  • La Escondida canyon
  • La Boca canyon
  • Lower Member
Spores
Krausellisporites
  • K. reissingeri
  • La Escondida canyon
  • La Boca canyon
  • Lower Member
SporesA Miospore, affinities with Selaginellaceae or Lycopodiaceae inside Lycopsida.
Nannoceratopsis
  • N. gracilis
  • La Escondida canyon
  • La Boca canyon
  • Lower Member
CystsA Dinoflajellate of the family Nannoceratopsiaceae inside Nannoceratopsiales
Ovalipollis
  • O. breviformis
  • La Escondida canyon
  • La Boca canyon
  • Lower Member
PollenA Pollen Grain, afinnities with Caytoniales inside Gymnospermopsida.
Pareodinia
  • P. sp.
  • La Escondida canyon
  • La Boca canyon
  • Lower Member
CystsA Dinoflajellate of the family Pareodinioideae inside Gonyaulacales
Quadraeculina
  • Q. anallaeformis
  • La Escondida canyon
  • La Boca canyon
  • Lower Member
PollenA Pollen Grain, affinities with Podocarpaceae and Pinaceae inside Coniferophyta.
Rhaetogonyaulax
  • R. rhaetica
  • La Escondida canyon
  • La Boca canyon
  • Lower Member
CystsA Dinoflajellate of the family Peridiniphycidae inside Dinophyceae
Spheripollenites
  • S. spp.
  • La Escondida canyon
  • La Boca canyon
  • Lower Member
PollenA Pollen Grain, affinities with the Hirmeriellaceae in the Pinopsida.
Vitreisporites
  • V. pallidus
  • V. bjuvensis
  • La Escondida canyon
  • La Boca canyon
  • Lower Member
PollenA Pollen Grain, afinnities with Caytoniales inside Gymnospermopsida.

Macroflora

GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Agathoxylon[27]
  • A. spp.
  • Huizachal-Peregrina Anticline
  • El Alamar Canyon
  • Lower Member
  • Fossil Wood
Affinities with Cheirolepidiaceae or Araucariaceae inside Pinales. Includes petrified wood logs up to 3.5 m in size
Cheirolepidium
  • C. sp.
  • Near Ciudad Victoria
  • Lower Member
  • Seed cones
Affinities with Cheirolepidiaceae inside Pinales.
Cephalotapsis
  • C. carolinensis
  • Novillo Canyon
  • Lower Member
  • Trunk Fragments
Affinities with Cupressaceae inside Pinales.
Cycadolepis
  • C. sp.
  • Near Ciudad Victoria
  • Lower Member
  • Cone scales
Affinities with Cycadeoidaceae inside Bennettitales.
Ctenophyllum
  • C. braunianum
  • Novillo Canyon
  • Lower Member
  • Leaflets
Affinities with Williamsoniaceae inside Bennettitales.
Laurozamites[28]
  • L. yaqui
  • Novillo Canyon
  • Lower Member
  • Leaflets
Affinities with Williamsoniaceae inside Bennettitales. Representative of large arboreal to low arbustive Bennetittes. The dominant foliar remain recovered on the formation, with up to 50 specimens
Otozamites
  • O. gramineus
  • Near Ciudad Victoria
  • Lower Member
  • Leaflets
Affinities with Williamsoniaceae inside Bennettitales.
Piazopteris[29] [30]
  • P. branneri
  • Novillo Canyon
  • Lower Member
  • Isolated Pinnae
Affinities with Matoniaceae inside Gleicheniales.
Podozamites
  • P. sp.
  • Novillo Canyon
  • Lower Member
  • Branched Shoots
Affinities with Krassiloviaceae inside Voltziales.

See also

Notes and References

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  2. Book: Bartolini . Claudio . Wilson . James Lee . Lawton . Timothy Frost . Mesozoic Sedimentary and Tectonic History of North-central Mexico . 1999 . Geological Society of America . Texas . 221 . 9780813723402 . 2 . 2 April 2022.
  3. Boschman . L. . Van Hinsbergen . D. J. . Langereis . C. G. . Molina-Garza . R. S. . Kimbrough . D. L. . Paleomagnetic Constraints on the Tectonic History of the Mesozoic Ophiolite and Arc Terranes of Western Mexico . AGU Fall Meeting Abstracts . 2017 . 2 . 2 . 345 . 2017AGUFM.T22B..05B . 2 April 2022.
  4. Martini . M. . Ortega-Gutiérrez . F. . Tectono-stratigraphic evolution of eastern Mexico during the break-up of Pangea: A review . Earth-Science Reviews . 2018 . 183 . 3 . 38–55 . 10.1016/j.earscirev.2016.06.013 . 2018ESRv..183...38M . 132691866 . 2 April 2022.
  5. Barboza-Gudiño . J. R . Zavala-Monsiváis . A. . Venegas-Rodríguez . G. . Barajas-Nigoche . L. D. . Late Triassic stratigraphy and facies from northeastern Mexico: Tectonic setting and provenance . Geosphere . 2010 . 6 . 5 . 621–640 . 10.1130/GES00545.1 . free .
  6. Mixon . R. B. . Murray . G. E. . Teodoro . D. G. . Age and Correlation of Huizachal Group (Mesozoic), State of Tamaulipas, Mexico . ADDENDUM. AAPG Bulletin . 1959 . 43 . 4 . 757–771 . 2 April 2022 . MainAges.
  7. Cisneros . I. I. R. . Holbrook . J. . Fluvial interpretations of stratigraphic surfaces across Upper Triassic to Lower-Middle Jurassic continental red beds northeastern Mexico . Journal of South American Earth Sciences . 2021 . 110 . 2 . 103366 . 10.1016/j.jsames.2021.103366 . 2021JSAES.11003366R . MAINASRT. free .
  8. Fastovsky . D. E. . Clark . J. M. . Strater . N. H. . Montellano . M. . Hopson . J. A. . Depositional environments of a Middle Jurassic terrestrial vertebrate assemblage, Huizachal Canyon, Mexico . Journal of Vertebrate Paleontology . 1995 . 15 . 3 . 561–575 . 10.1080/02724634.1995.10011249 . 2 April 2022.
  9. Montellano . M. . Hopson . J. A. . Clark . J. M. . Late Early Jurassic mammaliaforms from Huizachal Canyon, Tamaulipas, México . Journal of Vertebrate Paleontology . 2008 . 28 . 4 . 1130–1143 . 10.1671/0272-4634-28.4.1130 . 128782275 . 2 April 2022.
  10. Book: Fraser, Nicholas . Sues, Hans-Dieter . In the Shadow of the Dinosaurs: Early Mesozoic Tetrapods . Cambridge University Press . 1994 . 0-521-45242-2.
  11. Clark . J.M. . Hopson . J. A. . Distinctive mammal-like reptile from Mexico and its bearing on the phylogeny of the Tritylodontidae . Nature . 1985 . 315 . 8 . 398–400 . 10.1038/315398a0 . 1985Natur.315..398C . 4280605 . 2 April 2022.
  12. Clark . J. M. . A new burrowing diapsid from the Jurassic La Boca Formation of Tamaulipas, Mexico . Journal of Vertebrate Paleontology . 1994 . 14 . 2 . 180–195 . 10.1080/02724634.1994.10011551 . 2 April 2022.
  13. Reynoso . V. H. . Cruz . J. A. . Rivera-Sylva . H. E. . Carpenter . K. . Frey . E. . Mesozoic lepidosauromorphs of Mexico: a review and discussion of taxonomic assignments . Dinosaurs and Other Reptiles from the Mesozoic of Mexico . 2014 . 2 . 1 . 4–44 . 3 April 2022.
  14. Reynosa . V. . Descripcion de los esfenodontes del Jurasico temprano 0 medio de Canon Huizachal, Tamaulipas, Mexico . Unpublished M.Sc. Thesis, Instituto de Geologia, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico . 1992 . 2 April 2022.
  15. Reynoso . V. H. . A Middle Jurassic Sphenodon-like sphenodontian (Diapsida: Lepidosauria) from Huizachal Canyon, Tamaulipas, Mexico . Journal of Vertebrate Paleontology . 1996 . 16 . 2 . 210–221 . 10.1080/02724634.1996.10011309 . 2 April 2022.
  16. Reynoso . V. H. . Growth patterns and ontogenetic variation of the teeth and jaws of the Middle Jurassic sphenodontian Cynosphenodon huizachalensis (Reptilia: Rhynchocephalia) . Canadian Journal of Earth Sciences . 2003 . 40 . 4 . 609–619 . 10.1139/e02-097 . 2003CaJES..40..609R . 2 April 2022.
  17. Reynoso . V.H. . Possible evidence of a venom apparatus in a Middle Jurassic sphenodontian from the Huizachal red beds of Tamaulipas, Mexico . Journal of Vertebrate Paleontology . 2005 . 25 . 2 . 646–653 . 10.1671/0272-4634(2005)025[0646:PEOAVA]2.0.CO;2 . 131602253 . 2 April 2022.
  18. Reynoso. V.H. . Clark . J.M. . A dwarf sphenodontian from the Jurassic La Boca Formation of Tamaulipas, Mexico. . 1998 . Journal of Vertebrate Paleontology . 18 . 3. 333–339 . 10.1080/02724634.1998.10011061 . 2 April 2022.
  19. Clark . J. M. . Hopson . J. A. . Fastovsky . D. E. . Montellano . M. . Foot posture in a primitive pterosaur . Nature . 1998 . 391 . 6670 . 886–889 . 10.1038/36092 . 1998Natur.391..886C . 4408637 . 2 April 2022.
  20. Britt . B. B. . Dalla Vecchia . F. M. . Chure . D. J. . Engelmann . G. F. . Whiting . M. F. . Scheetz . R. D. . Caelestiventus hanseni gen. et sp. nov. extends the desert-dwelling pterosaur record back 65 million years . Nature Ecology & Evolution . 2018 . 2 . 9 . 1386–1392 . 10.1038/s41559-018-0627-y . 30104753 . 51984440 . 2 April 2022.
  21. Reynoso . V.H. . 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 . 2006 . 24 . 7 . 209–231 . 2 April 2022.
  22. Stiegler . J. . Hernández-Rivera . R. . Clark . James M. . Two Small Crocodyliformes from the Middle Jurassic La Boca Formation of Tamaulipas, Mexico . The Society of Vertebrate Paleontology 80th Annual Meeting · Virtual 2020 . 2020 . 80 . 1 . 32.
  23. Book: Clark, James . Montellano, Marisol . Hopson, James A. . Hernandez, Rene . Fastovsky, David A. . Fraser, N.C. . Sues H.-D. . An Early or Middle Jurassic tetrapod assemblage from the La Boca Formation, northeastern Mexico . In The Shadow of the Dinosaurs: Early Mesozoic Tetrapods . 1994 . Cambridge . Cambridge University Press . 295–302 . 0-521-45899-4.
  24. Munter . R. C. . Clark . J. M. . 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 . 2006 . 2 . 4 . 53–57 . 9780226094786 . 2 April 2022.
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  26. Rueda –Gaxiola . J. . Application of glauconite and fossil palynomorphs in reconstructing the Liassic paleogeography just before the opening of the Gulf of Mexico (Part I) . Iranian Journal of Earth Sciences . 2010 . 2 . 1 . 107–124 . 26 July 2023.
  27. Silva . Jorge . La tipología escalar como base de la correlación de la Aloformación La Boca y La Cuarcítica Cualac del anticlinorio de Huizachal-Peregrina, Tamaulipas con los grupos Consuelo y Tecocoyunca del anticlinorio de Tlaxiaco . Tesis de Licenciatura IPN . 2017 . 11 . 1 . 55 . 20 April 2023.
  28. Weber . R. . How old is the Triassic flora of Sonora and Tamaulipas and news on Leonardian floras in Puebla and Hidalgo, Mexico . Revista Mexicana de Ciencias Geológicas . 1997 . 14 . 2 . 225–243 .
  29. Silva-Pineda . A. . Buitrón-Sánchez . B. E. . Bartolini . C. . Mesozoic red bed floras in east-central Mexico and their stratigraphic relationships with marine beds . Geological Society of America . 1999 . 340 . 5 . 151–160. 2 April 2022.
  30. Eguiluz-de Antuñano . S. . Aranda-García . M. . Buitrón-Sánchez . B. E. . Las formaciones Gran Tesoro y Nazas: evolución de las secuencias Triásico Superior-Jurásico Inferior en México y su significado tectogenético . Boletín de la Sociedad Geológica Mexicana . 2014 . 66 . 3 . 507–539 . 10.18268/BSGM2014v66n3a8 . free .