Dinosaur undertrack specimens from Upper Jurassic of Spain + paleoenvironment of Upper Jurassic dinosaur tracks from Morocco

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

New dino tracks papers:

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Free pdf:

Laura Piñuela, José Carlos García-Ramos, Karen Moreno, Giuseppe Leonardi & Oscar Eugenio Finsterbusch-Lagos (2025)
Exceptional and striking 3D track-detached undertrack specimens from the Upper Jurassic of  Asturias (N Spain).
Rivista Italiana di Paleontologia e Stratigrafia 131(1): 11-24
DOI: https://doi.org/10.54103/2039-4942/23711
https://riviste.unimi.it/index.php/RIPS/article/view/23711

Free pdf:
https://riviste.unimi.it/index.php/RIPS/article/view/23711/23451


Vertebrate palaeoichnology often aims at the identification of the trackmaker by associating diagnostic features from the known taxa’s skeletal anatomy with its inferred footprint morphology, but deep penetrative tracks and/or deep, detached undertracks (DDU) are providing conflicting morphological/extra-morphological information, bringing into question the initially assumed close anatomical correlation.

Penetrative footprints produced in fluvial-dominated deltaic facies from Upper Jurassic Lastres Formation are very frequent in the coastal cliffs of Asturias (N Spain). Some of them consist of non-avian theropod track casts associated with “ornithopod-like” detached undertracks. Some criteria are suggested to distinguish the latter when such an association does not exist.

Moreover, we describe an exceptional theropod footprint preserved as a sandstone cast along with its respective deep detached sandstone undertrack (DDSU). The specimen records the foot movement through the sediment, entailing striking morphologic changes in outline along four different levels of depth. The uppermost level 1 shows an apparent stegosaur hind track morphology; level 2 resembles an avian-theropod print; level 3 represents the true non-avian theropod pedal morphology of the trackmaker; the lowermost level 4 corresponds to the deep detached sandstone undertrack (DDSU), which could be interpreted as either a track of a graviportal theropod or an ornithopod-like footprint.

In light of this new evidence, it becomes clear that vertebrate ichnotaxonomy should not be based solely on the supposed trackmaker identification. Furthermore, biogeographic and evolutionary studies linked to this core information should be considered unsupported, along with many ichnotaxonomical assignations based on taphonomic processes, such as the case exemplified herein, the Iguanodontipus ichnogenus.

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Reolid M, Reolid J, Laita E, Boutakiout M, Masrour M & Pérez-Lorente F (2025)
Palaeoenvironmental and palaeoclimatic characterization of Upper Jurassic sedimentary sequences with dinosaur footprints of the M’Goun Geopark (High Atlas, Morocco).
Journal of African Earth Sciences 105539
doi: https://doi.org/10.1016/j.jafrearsci.2025.105539
https://www.sciencedirect.com/science/article/abs/pii/S1464343X25000068


Highlights

Sedimentary sequences of Iouaridène Formation show cyclicity capped by silcretes
Hard silcretes represent hiatuses with formation of mudcracks and dinosaur footprints
Ciclicity marked by changes in quartz and clay content, and Sr/Ba and Zr/Rb ratios
Mineralogy and geochemistry reveal an upwards trend to increasingly aridity
Record of silcretes ends when returned more humid and deeper lacustrine conditions

Abstract

The Iouaridène Formation (Upper Jurassic, High Atlas, Morocco) is a relevant area for the study of dinosaur footprints, but up to now little is known about the palaeoenvironmental conditions at the time of its formation. This work consists of a sedimentological, geochemical, and mineralogical study of part of the sedimentary succession of the Iouaridène Formation, especially Units B and C. The cyclic sedimentation pattern in Unit B, characterized by alternating soft claystones and siltstone layers and hard sandstone layers with ripples and mudcracks, reflects a dynamic environment shaped by recurring flooding and emersion events. This cyclicity is marked by fluctuations in quartz, clay and analcime content, leading to sedimentary sequences capped by silcretes, which indicate sedimentation hiatuses. The formation of mudcracks and the preservation of dinosaur footprints further highlight the depositional conditions. Mineralogical and geochemical analyses reveal an upwards trend to increasingly arid conditions during the deposition of Unit B, with an increase in quartz and decrease in kaolinite, as well as palaeoclimatic geochemical proxies. The presence of analcime supports a lacustrine environment under arid or semi-arid conditions and fluctuations in the alkalinity of pore waters. The CIA and CIW values reflect moderate to weak weathering congruent with the arid conditions indicated by other proxies. Decreasing C-values towards the top of the section points to environmental changes from semi-arid toward more arid conditions. Other indexes of salinity and aridity (Sr/Ba and Zr/Rb ratios), also support the trend towards increasing aridity in Unit B. In contrast to this, Unit C indicates more humid and deeper conditions, marked by the record of cross-bedding, lacustrine ostracods and fish bones, and the absence of mudcracks, silcretes, and dinosaur footprints. This variability underscores the dynamic climatic and environmental history of the Iouaridène Formation, reflecting the final phase of the Atlasic Basin fill during the late Jurassic. This is the first work on the palaeoclimatic conditions of the Iouaridène Formation and the first study that integrates sedimentology, geochemistry and mineralogy of this formation. These findings enhance the understanding of the geological evolution of the Jurassic of the M’Goun Geopark and set the background for future research on the area to explore the interactions between climatic conditions, sedimentary processes, and biological activity in Jurassic lacustrine environments.

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[Gregory Paul]

Does anyone know where the original fossil skull this cast is based on is? 

https://www.istockphoto.com/photo/velociraptor-skull-gm178100372-24612059?searchscope=image%2Cfilm

https://www.clemson.edu/public/geomuseum/research_collections/index.html

Is it in a museum? Or is it in private hands? 

And what is the story of the above skeleton at the Bob Campbell museum? 

GSPaul