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“Pegadas de mula”: An explanation for the occurrence of Mesozoic traces that resemble mule tracks

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Abstract

Large semicircular traces and markings that resemble tracks made by horses or mules wearing horseshoes, have been a source of much confusion in the paleontological literature. Study of these traces has followed a convoluted trail from thirteenth century Portuguese folklore to purported Deinonychus tracks in Uzbekistan and China, to creationist preachings in North America. We show that these traces or markings, which occur in many Phanerozoic deposits, but especially in the Mesozoic, are in most cases examples of the well known burrow Rhizocorallium, or examples of current crescents.Although these traces do bear a remarkable resemblance to tracks made by mules or horses (wearing “horseshoes"), such interpretations are obviously out of the question, for pre‐Cenozoic deposits, even though they have provided fuel for creationists. We herein show that the enigmatic trace fossil Gumatagichnus ungliformis from the Cenomanian of Uzbekistan is a Rhizocorallium burrow of invertebrate, not vertebrate, origin. Similar traces from the Upper Jurassic of Portugal and elsewhere, are also invertebrate in origin, even though they may occur in association with vertebrate tracks. The enigmatic Lower Jurassic trace fossil Hoplichnus, and similar Triassic markings/traces from terrestrial deposits have also been interpreted as Rhizocoralliumlike trace fossils, but may, in some cases, be inorganic sedimentary structures such as current crescents. The orientation and sedimentological/stratigraphic context of these traces/markings is important in distinguishing their origin.
... Dickas (2018, p. 249) misidentified three aligned Diplocraterion burrows from the Red Gulch Dinosaur Tracksite as a theropod track because of their coincidently tridactyl arrangement. Horseshoe-shaped invertebrate burrows attributable to the Rhizocorallium have been repeatedly confused with tetrapod tracks (Hitchcock 1858; Gabunia et al. 1988;Lockley et al. 1994). Sedimentary structures such as sand crescents (Lockley et al. 1994) and eroded gypsum nodules (Falkingham et al. 2021) may potentially be confused with tracks in some cases. ...
... Horseshoe-shaped invertebrate burrows attributable to the Rhizocorallium have been repeatedly confused with tetrapod tracks (Hitchcock 1858; Gabunia et al. 1988;Lockley et al. 1994). Sedimentary structures such as sand crescents (Lockley et al. 1994) and eroded gypsum nodules (Falkingham et al. 2021) may potentially be confused with tracks in some cases. ...
... One of the best examples are the sauropod trackways and the trace fossil Rhizocorallium of Cape Espichel (Portugal), object of curiosity and devotion since the thirteenth century. Fishermen from the region of Sesimbra interpreted such trace fossils as the footprints of a giant mule that carried the Virgin Mary (Lockley et al., 1994). During the eighteenth century, a sanctuary was erected and "Nossa Senhora da Pedra Mua" (Our Lady of the Mule Stone) became an object of national worship (Fig. 1C). ...
... Ilmenichnus Hecker, 1980 is now considered a junior synonym of Rhizocorallium (Knaust, 2013). Hoplichnus Hitchcock, 1848 is a poorly understood ichnogenus, comprising horseshoe-shaped structures that have been subsequently compared with Rhizocorallium, although no visible spreiten are present (Lockley et al., 1994;Knaust, 2013). For the present study it has been considered a nomen dubium and has not been included in our compilation. ...
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Ichnodisparity has been recently introduced as a concept to assess the variability of morphologic plans in biogenic structures, revealing major innovations in body plan, locomotory system and/or behavioral program. Whereas ichnodiversity is measured in terms of the number of ichnotaxa (i.e. ichnogenera or ichnospecies), ichnodisparity is evaluated based on the identification of categories of architectural design. Seventy-nine categories of architectural designs (58 for bioturbation structures and 21 for bioerosion structures), encompassing 523 ichnogenera (417 for bioturbation structures and 106 for bioerosion structures), are defined. They are restricted to invertebrate ichnotaxa, whereas vertebrate trace fossils were not included. Although the scheme is designed to be comprehensive, the proposed categories are necessarily works in progress because of the state of flux in ichnotaxonomy and the need to adjust the definitions of categories according to the scope and scale of the analysis. Although it may be said that the establishment of categories of architectural design is to a certain degree a subjective enterprise, this is not different from ichnotaxonomy because classifying trace fossils from a taxonomic perspective implies observing the morphology of the trace and interpreting it in terms of behavior. The concept of ichnodisparity is free of some of the vagaries involved in ichnotaxonomy. The fact that ichnodiversity and ichnodisparity exhibit different trajectories during the Phanerozoic underscores the importance of adding the latter to the ichnologic toolkit.
... Os Rhizocorallium são marcas fossilizadas em forma de ferradura, feitas por invertebrados marinhos do Mesozoico. Em Paúla, no Concelho de Alenquer, existe uma laje do Jurássico Superior com estes icnofósseis que foram interpretados como pegadas de cavalo, devido à forma de ferradura que apresentam (Lockley et al. 1994). Os Rhizocorallium aparecem noutras zonas de Portugal, como por exemplo a placa de calcário com cerca de 1 metro de comprimento que está no Museu Geológico de Lisboa, proveniente de uma formação do Cretácico de Aveiro. ...
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Since Prehistory man has “crossed” with fossils. Our ancestors wanted to know and understand the world and nature, but when they observed fossil remains generally they interpreted it on the basis of the reality surrounding them and on religious beliefs. 3e trace fossils (icnofossils) of large vertebrates, in particular the dinosaurs are at the origin of several legends, some of them associating the footprints of these animals to giant horses and relating them with religion, such as the legend of the footprints of Pedra da Mua, in Cabo Espichel.
... One of the best examples are the sauropod trackways and the trace fossil Rhizocorallium of Cape Espichel (Portugal), object of curiosity and devotion since the thirteenth century. Fishermen from the region of Sesimbra interpreted such trace fossils as the footprints of a giant mule that carried the Virgin Mary (Lockley et al., 1994). During the eighteenth century, a sanctuary was erected and "Nossa Senhora da Pedra Mua" (Our Lady of the Mule Stone) became an object of national worship (Fig. 1C). ...
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Although the concept of ichnology as a single coherent field arose in the nineteenth century, the endeavor of understanding traces is old as civilization and involved cultural areas worldwide. In fact, fossil and recent traces were recognized since prehistoric times and their study emerged from the European Renaissance. This progression, from empirical knowledge toward the modern concepts of ichnology, formed a major research field which developed on a global scale. This report outlines the history of ichnology by (1) exploring the individual cultural areas, (2) tracing a comprehensive bibliographic database, and (3) analyzing the evolution of ichnology semiquantitatively and in a graphical form (" tree of ichnology"). The results form a review and synthesis of the history of ichnology, establishing the individual and integrated importance of the different ichnological schools in the world.
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Ghadamgahs are sacred places in Iran date back to ancient and historical eras, serving as symbols of Islamic and cultural heritage. Usually, sculpted human footprints at these sites are mostly attributed to the journey across Iran by the Eighth Imam Ali ibn Musa al-Reza AS (765-818 CE). Ghadamgahs are relatively abundant in southern provinces of Iran, such as Fars, Khuzestan, and Bushehr. In the present study, the footprints of some of Ghadamgahs and their relationships with natural footprints are investigated. Besides, the spatial location of Ghadamgahs with water resources is evaluated. The data were gathered based on the available reports as well as the observation of some footprints in Ghadamgahs. The results show that although the natural footprints of humans have been reported from many parts of the world, the type of rock and the geometry of the footprints in Ghadamgahs are evidence of their handiwork and artificiality. Traces of natural footprints are found in sedimentary rocks or pyroclastic rocks (volcanic ash). Meanwhile, the pedestals installed in Ghadamgahs have also been carved on igneous or metamorphic rocks. However, the role of footprints in Ghadmagah is historically reminiscent of the presence of Imam Reza (AS) and the descendants of Imams are miraculously engraved in stone. Ghadamgahs in Iran are often built near springs and water sources and are somewhat associated with the sanctity of water in Iran. Keeping water clean in Iran is associated with ritual approaches and historical-religious beliefs, and the construction of Ghadamgahs shows the efforts of Iranians in this direction. Introduction Holy places are known as respected areas for the people of most religions. Usually, particular ceremonies are executed and special symbols are installed in these places. One of these places is Ghadamgah in Iranian religious folklore, which is known as a holy shrine usually with a footprint slab as a symbol of the presence of religious people. Greeting and bowing, touching, kissing, circumambulating, praying, lighting candles, and lighting fires or the use of fragrant substances are pilgrimage ceremonies in Ghadamgahs. In the present study, the authors evaluate the nature of the footprints in Ghadamgahs. Also, the location of Ghadamgahs to the natural phenomena, mainly water resources is examined. Materials and Methods Natural human footprints have been found in the Quaternary sediments in the world. These footprints and trackways are preserved on the sedimentary rocks and some cases in the volcaniclastic rocks. The biological and sedimentological factors, such as the weight of a human, nature of walking, and the grain size of sediments. To gather the data of the present study, one of the authors of the present study studied some of Ghadamgahs in Iran and other countries that included Ghadamgah of Nishapur, Ghadamgah of Shamil area in Hormozgan province, Ghadamgah of Abhar in Zanjan province, Ghadamgah of Salman and Ali in Arzhan area in Fars province, Ghadamgah of Takeh Mo'aven-ol Molk of Kermanshah, Ghadamgah of prophet Muhammad in Topkapi Museum of Istanbul, and Ghadamgah of prophet Abraham in Mecca. However, based on field data, installed footprint slabs in the Ghadamgah do not include natural footprint, and all of them are handmade because they differ by geometrical indexes, the morphology of footprints, and host rocks against the natural human footprints. The present study aims to answer the following questions: 1. What is the origin and preservation of human footprints? 2. What is the geographical distribution of the most important Ghadamgahs in Iran? 3. Does the existence of a Ghadamgah attributed to the Prophet, Imam, Imamzadeh or holy people indicate their presence in that area and how can such a presence be historically proven? 4. What is the relationship between pedestrians and natural phenomena, mainly water resources, in Iran? Discussion of Results and Conclusions The results of the present study showed that natural human footprints are formed on soft sediments and changed to sedimentary rocks by the diagenesis processes, over geological periods. Therefore, natural footprints can only be found in sedimentary rocks or some cases in the volcaniclastic deposits. Natural footprints have a definite geometry and arrangement, while hand-carved and carved footprints may vary in type of rock, size, and geometry. Footprints are the simplest human remains and their attribution to important or sacred persons is credible to the general public. The installation of handmade footprint slabs in the footsteps has guaranteed and justified the sanctity of that place. Additionally, the validity of the attributed ancient passageways to the Infallibles, especially to Imam Reza's (AS) migration from Arabia to Central Asia, and the study of their historical presence in the place by the Ghadamgahs in Iran, are validated by specifying the narration of the names of the cities and places and symbolized by the handicraft footprints. Historians and archaeologists may be interested in the reconstruction of the historical passageways and the location of ancient routes. Finally, the proximity of most Iranian worships, such as Ghadamgahs, along water resources, shows the importance of water resources and efforts to popularize water resources through religious beliefs.
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