Elusive Cretaceous Gondwanan theropods: The footprint evidence from central Argentina

New dinosaur (theropod and sauropod), crocodylomorph and swim tracks from Upper Jurassic units of the Lusitanian Basin, housed at the Sociedade de História Natural in Torres Vedras, are here described. They were collected from three different geological formations, the Praia da Amoreira‐Porto Novo (upper Kimmeridgian) and the Alcobaça (Kimmeridgian‐lower Tithonian) formations in the Consolação Sub‐basin and the Freixial Fm. (middle‐upper Tithonian) in the Turcifal Sub‐basin. Four different theropod morphotypes are identified as follows: cf. Jurabrontes isp., Megalosauripus cf. transjuranicus, Grallatoridae indet. and an indeterminate morphotype (Theropoda indet.) that have affinities with other Therangospodus‐like tracks described in Europe. An indeterminate sauropod track is also identified. These five morphotypes suggest high saurischian dinosaur ichnodiversity, similar to that seen in other European Late Jurassic areas (e.g. the Swiss Jura Mountains), but represent just a portion of the higher diversity exhibited by the osteological record in the Lusitanian Basin. Further, one crocodylomorph pes track identified as Crocodylopodus isp. and swim tracks assigned to Characichnos isp., possibly also produced by crocodylomorphs, are also identified. The newly identified ichnotaxa, together with the older and other recent identifications, indicate ichnodiversity comparable with the richest coeval Upper Jurassic units.

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“…(Lull 1904; Melchor et al . 2019); thus, the possibility that there are different grallatorid ichnotaxa in the Lusitanian Basin remains open.…”

Section: Discussionmentioning

confidence: 99%

New dinosaur, crocodylomorph and swim tracks from the Late Jurassic of the Lusitanian Basin: implications for ichnodiversity

Castanera

Malafaia

Silva

et al. 2021

LET

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“…Moreover, the studied theropod trackways present a higher stride and pace and a lower pace angle than this ichnotaxon. The ichnogenus Picunichnus, whose diagnosis was amended by Melchor et al (2019), includes the aforementioned P. benedettoi from the Candeleros Formation and the type ichnospecies Picunichnus quijadaensis Melchor, 2019, from the Albian Lagarcito Formation (San Luis, Argentina). The icnotaxon Picunichnus presents marked elongation (FL/FW ratio ranges between 1.5 and 2.15) and moderate to marked mesaxony (AT l/w ratio ranges between 0.6 and 0.9).…”

Section: Ichnotaxonomymentioning

confidence: 99%

“…In order to assign an ichnotaxonomical status to the studied theropod tracks, they are compared with the ichnotaxa that are generally considered as valid (see Razzolini et al, 2017;Marty et al, 2018;Melchor et al, 2019).…”

Section: Ichnotaxonomymentioning

confidence: 99%

“…The ichnofamily Grallatoridae Lull, 1904, includes ichnogenera such as Grallator Hitchcock, 1858; Anchisauripus Lull, 1904, Prototrisauropus Ellenberger, 1970, and Picunichnus Calvo, 1991 comprises typically tridactyl (occasionally tetradactyl) footprints displaying moderate to marked elongation (FL/FW ratio > 1.50) and moderate to marked mesaxony (AT l/w ratio > 0.6) sensu the emended diagnosis by Melchor et al (2019). In reference to these two parameters, the present theropod footprints exhibit a FL/FW ratio lower than 1.4 and a mean AT l/w ratio lower than 0.6.…”

Section: Ichnotaxonomymentioning

confidence: 99%

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Gregarious behaviour among non-avian theropods inferred from trackways: A case study from the Cretaceous (Cenomanian) Candeleros Formation of Patagonia, Argentina

Heredia

Díaz-Martínez

Pazos

et al. 2020

Palaeogeography, Palaeoclimatology, Palaeoecology

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This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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“…To circumvent such issues, 3D techniques such as photogrammetry and light detection and ranging (LiDAR) have recently been introduced for digitizing and recording dinosaur footprints [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Furthermore, Lallensack [27] produced a program to create objective track outlines from 3D footprints in R environment.…”

Section: Introductionmentioning

confidence: 99%

Classification of large ornithopod dinosaur footprints using Xception transfer learning

Ha,

Kim

2023

PLoS ONE

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Large ornithopod dinosaur footprints have been confirmed on all continents except Antarctica since the 19th century. However, oversplitting problems in ichnotaxa have historically been observed in these footprints. To address these issues and distinguish between validated ichnotaxa, this study employed convolutional neural network-based Xception transfer learning to automatically classify ornithopod dinosaur tracks. The machine learning model was trained for 162 epochs (i.e., the number of full cycles of all training data through the model) using 274 data images, excluding horizontally flipped images. The trained model accuracy was 96.36%, and the validation accuracy was 92.59%. We demonstrate the performance of the machine learning model using footprint illustrations that are not included in the training dataset. These results show that the machine learning model developed in this study can properly classify footprint illustration data for large ornithopod dinosaurs. However, the quality of footprint illustration data (or images) inherently affects the performance of our machine learning model, which performs better on well-preserved footprints. In addition, because the developed machine-learning model is a typical supervised learning model, it is not possible to introduce a new label or class. Although this study used illustrations rather than photos or 3D data, it is the first application of machine-learning techniques at the academic level for verifying the ichnotaxonic assignments of large ornithopod dinosaur footprints. Furthermore, the machine learning model will likely aid researchers to classify the large ornithopod dinosaur footprint ichnotaxa, thereby safeguarding against the oversplitting problem.

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Elusive Cretaceous Gondwanan theropods: The footprint evidence from central Argentina

Cited by 9 publications

References 46 publications

New dinosaur, crocodylomorph and swim tracks from the Late Jurassic of the Lusitanian Basin: implications for ichnodiversity

New dinosaur, crocodylomorph and swim tracks from the Late Jurassic of the Lusitanian Basin: implications for ichnodiversity

Gregarious behaviour among non-avian theropods inferred from trackways: A case study from the Cretaceous (Cenomanian) Candeleros Formation of Patagonia, Argentina

Classification of large ornithopod dinosaur footprints using Xception transfer learning

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