Fig 5 - uploaded by David B. Loope
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Sketch of the trackway in figure 4. The sketch is redrawn from high−resolution digital photographs of the trackway. RM, right manus; LM, left manus; RP, right pes; LP, left pes. The solid arrow indicates the direc− tion of progression and the broken−line arrow the orientation of the body during progression. Notice how the animal walked at an oblique angle upslope in the first half of the trackway, and then changed to progress head on, up the slope.
Source publication
Milàn, J., Loope, D.B., and Bromley, R.G. 2008. Crouching theropod and Navahopus sauropodomorph tracks from the Early Jurassic Navajo Sandstone of USA. Acta Palaeontologica Polonica 53 (2): 197-205. Numerous tracks and trackways are preserved in the a cross−strata of the Lower Jurassic Navajo Sandstone of northern Arizona and southern Utah, USA. Tr...
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Citations
... Sereno, 2006)) tracks are rare (e.g., Hunt & Lucas, 2006a;Hunt & Lucas, 2006b;Klein & Lucas, 2021;Lockley & Gierliński, 2006;Lockley & Gierliński, 2014;Lockley, Kirkland & Milner, 2004). However, non-synapsid tetrapod tracks also are relatively common in eolian settings in the region (e.g., Baird, 1980;Bennett, Harris & Milner, 2023;Hamblin, Bilbey & Hall, 2000;Lockley et al., 2014;Lockley et al., 2021a;Lockley et al., 2021b;Milàn, Loope & Bromley, 2008;Milner et al., 2011;Milner et al., 2023a;Stokes & Madsen Jr, 1979). Furthermore, burrows attributed to synapsids are also known exclusively from eolian facies in this region (e.g., Hasiotis, Parrish & Chan, 2019;Odier, 2006;Riese, Hasiotis & Odier, 2011). ...
... Thus, the SGDS tracks do not fit within the Ameghinichnus paradigm. , 1980 (Fig. 10C) Navahopus is an uncommon ichnotaxon thus far reported exclusively from Lower Jurassic strata of the southwestern United States (Baird, 1980;Hunt & Lucas, 2006c;Milàn, Loope & Bromley, 2008;Reynolds, 2006). The Navahopus track maker is unclear: the tracks have been attributed to sauropodomorph dinosaurs (Baird, 1980;Milàn, Loope & Bromley, 2008) and large therapsid synapsids (Hunt & Lucas, 2006c;Lockley & Hunt, 1995;Shibata, Matsukawa & Lockley, 2006). ...
... , 1980 (Fig. 10C) Navahopus is an uncommon ichnotaxon thus far reported exclusively from Lower Jurassic strata of the southwestern United States (Baird, 1980;Hunt & Lucas, 2006c;Milàn, Loope & Bromley, 2008;Reynolds, 2006). The Navahopus track maker is unclear: the tracks have been attributed to sauropodomorph dinosaurs (Baird, 1980;Milàn, Loope & Bromley, 2008) and large therapsid synapsids (Hunt & Lucas, 2006c;Lockley & Hunt, 1995;Shibata, Matsukawa & Lockley, 2006). Navahopus manus tracks are tridactyl, with two short, anteriorly oriented digit imprints and a large, laterally oriented, ''falciform'' claw imprint (Baird, 1980;Milàn, Loope & Bromley, 2008;q.v., Hunt & Lucas, 2006c). ...
Eight fossil tetrapod footprints from lake-shore deposits in the Lower Jurassic Moenave Formation at the St. George Dinosaur Discovery Site (SGDS) in southwestern Utah cannot be assigned to the prevalent dinosaurian (Anomoepus, Eubrontes, Gigandipus, Grallator, Kayentapus) or crocodyliform (Batrachopus) ichnotaxa at the site. The tridactyl and tetradactyl footprints are incomplete, consisting of digit- and digit-tip-only imprints. Seven of the eight are likely pes prints; the remaining specimen is a possible manus print. The pes prints have digit imprint morphologies and similar anterior projections and divarication angles to those of Brasilichnium, an ichnotaxon found primarily in eolian paleoenvironments attributed to eucynodont synapsids. Although their incompleteness prevents clear referral to Brasilichnium, the SGDS tracks nevertheless suggest a eucynodont track maker and thus represent a rare, Early Mesozoic occurrence of such tracks outside of an eolian paleoenvironment.
... Nevertheless, current data suggests that the AAT is a vertebrate tracksite of major paleontological significance. Eubrontes is currently the most abundant dinosaur ichnotaxon in the Navajo Sandstone (e.g., Lockley et al., 2021), though Grallator and, less commonly, Anomoepus, Otozoum, Navahopus, and Moyenisauropus also have been recognized at other tracksites (Hamblin & Bilbey, 1999;Hunt & Lucas, 2006;Lockley et al., 2021;Lockley & Gierliński, 2006, 2014Milàn et al., 2008;Rainforth, 1997Rainforth, , 2003. Several non-dinosaurian ichnotaxa known from elsewhere in the Navajo Sandstone, such as Pteraichnus (Stokes & Madsen, 1979) and Brasilichnium (Lockley, 2011), also have not yet been recognized at the AAT. ...
In November 2018, a team of researchers from the National Park Service and the St. George Dinosaur Discovery Site documented fossil vertebrate tracks at the Andre’s Alcove Tracksite (AAT) in the Lower Jurassic (?190–185 Ma) Navajo Sandstone in Glen Canyon National Recreation Area, Utah. The tracks at the AAT were photo-documented for photogrammetric processing using Agisoft Photoscan Professional to enable the track surface to be studied remotely. Ichnotaxa already identified at the AAT include those of small ornithischian dinosaurs ( Anomoepus ), theropod dinosaurs ( Grallator , Eubrontes ), and protosuchian crocodylomorphs ( Batrachopus ). Vertebrate body fossils are rarer in the Navajo Sandstone than in underlying, earlier Jurassic strata; the AAT site therefore provides important insights into late Early Jurassic vertebrate diversity and behaviors at the onset of the Navajo Erg in the American Southwest.
... Furthermore, the overall shape of 1.2 (1) is better defined than track 1.1 (1) , which is wider than track 423 1.2 (1) . This widening probably is due to the transmission of the deformation over the successive 424 underlying layers that makes the undertrack wider than the true track (Milàn and Bromley, 2008). 425 ...
Several dinosaur tridactyl tracks showing inter- and intra-trackways morphological variations from the Cenomanian Candeleros Formation of the Neuquén Basin, Argentina, have been documented. Footprints occur on three different stratigraphic levels and are impressed on medium-grained sandstone of fluvial origin. Level 1 includes deep tridactyl tracks with metatarsal impressions (average length of 31 cm) preserved as true tracks and undertracks that could have been generated due to simply sinking of the pes into a soft substrate and also probably by a continuous walk in a squatting position. Level 2 shows the largest tridactyl tracks (average length of 58 cm) recognized in this work, situated a few meters close to an already studied sauropod trackway. The different preservation between these bipedal and quadrupedal tracks could be explained due to different substrate properties and dissimilarities of the pedal shape between trackmakers. Level 3 comprises small to large tridactyl tracks (length from 6 to 34 cm) including intra-trackway morphological variation, that is interpreted as a result of changes in the substrate properties, mainly moisture content, along the tracking surface. Taking into account that the footprints studied here are poorly preserved, they were not assigned to any particular ichnotaxon. The large tridactyl tracks have been attributed to carcharodontosaurid theropod trackmakers while medium and small tracks to undetermined bipedal dinosaur. One pair of these large theropod tracks was closely documented on the same tracking surface of the aforementioned studied sauropod trackway, attributed to rebbachisaurids. This suggests that both carcharodontosaurid and rebbachisaurid trackmakers coexisted in the same habitats as the osteological record noted. This tracksite represents an example of the morphological variability of dinosaur tridactyl tracks controlled mainly by the substrate properties, and how an approach aimed at understanding footprint formation and preservation is necessary before beginning ichnotaxonomical studies,
among others.
... Fossils are mostly associated with interdunal environments (Loope et al. 2004b). As time went on during the deposition of the Navajo Sandstone, the climate became drier (Irmis 2005b), although there were several wetter periods with durations on the order of tens of thousands of years (Milan et al. 2008). While dating of Glen Canyon Group units has proven difficult, the Navajo Sandstone has generally been dated to the middle and late Early Jurassic , sometime between approximately 190 and 175 Ma, but recent dating indicates that the lower Navajo Sandstone is as old as 200.5 ± 1.5 Ma (Parrish et al. 2019). ...
... Vertebrate trace fossils are much more common than body fossils in the Navajo Sandstone, and have been extensively described from localities primarily in Utah. More than 60 dinosaur track sites are known in the Navajo Sandstone across its depositional area (Loope 2006;Milan et al. 2008). The various vertebrate trace fossils have gone under different names and interpretations, depending on the author. ...
... The various vertebrate trace fossils have gone under different names and interpretations, depending on the author. Recent works (Irmis 2005b;Hunt and Lucas 2006;Loope 2006) have settled on several primary ichnogenera: Brasilichnium (synapsid, but see Milan et al. 2008 for an interpretation as a sauropodomorph dinosaur), Batrachopus (crocodile relative), Grallator (small theropod dinosaur), Anchisauripus (medium theropod), Eubrontes (large theropod), Navahopus (small ?sauropodomorph), Otozoum (larger sauropodomorph), and Anomoepus (ornithischian dinosaur) (Irmis 2005b). ...
This is a comprehensive inventory of paleontological resources in Grand Canyon-Parashant National Monument.
... Discussion. Tridactyl footprints with more or less extensive metatarsal impressions have been documented from numerous sites (e.g., Kuban, 1989;Lockley et al., 2003Lockley et al., , 2006Milàn et al., 2008;Milner et al., 2009;Wilson et al., 2009;Farlow et al., 2012;Perez-Lorente, 2015;Xing et al., 2015a;Citton et al., 2015;Romano and Citton, 2017). They have been explained by these authors as the result of: 1) walking in a plantigrade manner; 2) soft substrate, where metatarsals were registered because the foot was deeply sinking in; 3) sitting (crouching or squatting) position, sometimes even leaving a mark of the ischium or the tail, when the left and right foot was impressed side by side. ...
... The sharp triangular deformation, the spatial relationship between the three deformations and the structureless cores of the deformations could indicate that they formed as consequence of the foot print of the fingers of a theropod dinosaur (cf. Milàn et al., 2008). Similar structures have been described in detail by Loope (2006) in the Jurassic Navajo Sandstone in the US, where (i) a central "shaft" of the tracks is recognized together with (ii) folded substrate in the laterals and (iii) a central downfold (see Loope, 2006) as those observed from the Cretaceous of China ( Fig. 3A and B). ...
... Ichnites on the Ha Nohana palaeosurface are preserved as two morphotypes that can be attributed with variable certainty to theropod-like trackmakers. Moreover, morphotype II displays anatomical details of the trackmaker's foot that are not common with respect to most tridactyl morphologies but are well-documented in the ichnological record of theropods (e.g., Kuban, 1989;Olsen et al., 1998;Gatesy et al., 1999;Gatesy, 2003;Lockley et al., 2003;Nicosia et al., 2007;Milàn et al., 2008;Lockley et al., 2013;Citton et al., 2015;Romano and Citton, 2016;Citton et al., 2017). Here, the metatarsal and digit I are present in the track impression suggesting that as the animal's foot sunk a significant amount into the substrate and probably had to walk while waddling through the water-logged sand. ...
The Ha Nohana palaeosurface in southern Lesotho preserves tridactyl and tetradactyl tracks and trackways attributable to Early Jurassic bipedal, theropod-like dinosaurs. Complementary sedimentological and ichnological observations along the palaeosurface and in the strata below and above it allow detailed interpretations
of climatically driven changes in this southern Gondwana palaeoecosystem. Sedimentological evidence suggests
trackmaking under a semi-arid climate with heavy storms and episodic flash flooding that induced ephemeral,
unconfined sheetwashes. The palaeosurface is overlain by rhythmically bedded, organic-matter rich mudstones
that formed in a deep, stratified lake indicative of a longer and wetter period in the history of the site. The unique
morphological details of the Ha Nohana tracks help refine the properties of the substrate during track making, the
ichnotaxonomic affinities of the footprints and the interpretation of the foot movement relative to the substrate.
Two footprint morphotypes, ~ 300 m apart, are defined on the palaeosurface. Tracks of morphotype I are tridactyl,
shallow, contain digital pad impressions and were impressed on a firm, sand rippled substrate that underwent desiccation. Conversely, tracks of morphotype II are tetradactyl, deep, and have an elongated posterior region. These
tracks are preserved on the surface of a massive sandstone and are associated with soft sediment collapse structures
related to the animal’s foot sinking into the water-saturated, malleable sediment layer. Morphotype II tracks show
that as the animal waded across the substrate, the liquefied sediment lost its cohesive strength and could only
partially support the weight of the animal. In so doing, the animal’s foot sunk deep enough into the sediment such
that the impression of the metatarsal and digit I (hallux) are now visible. Thus, the palaeosurface was walked on by
small-to-medium sized theropods that traversed over ripple marks in firmer moist sand, as well as a larger theropod
that tottered through water-logged sand.
... The reinterpretation of the claw traces of Navahopus approximates this ichnogenus morphologically to the Chelichnopodidae. Actually, several authors noted the similarity between Navahopus and Brasilichnium Reynolds, 2006;Lockley & Tedrow, 2009;Lockley, 2011), including Milàn, Loope & Bromley (2008), who reinterpreted a trackway previously attributed to Brasilichnium by Loope & Rowe (2003) as a different ichnospecies of Navahopus (N. coyoteensis). ...
Tetrapod tracks in eolianites are widespread in the fossil record since the late Paleozoic. Among these ichnofaunas, the ichnogenus Chelichnus is the most representative of the Permian tetrapod ichnological record of eolian deposits of Europe, North America and South America, where the Chelichnus Ichnofacies often occurs. In this contribution, we describe five sets of tracks (one of which is preserved in cross-section), representing the first occurrence of Dicynodontipus and Chelichnus in the “Pirambóia Formation” of southern Brazil. This unit represents a humid desert in southwestern Pangea and its lower and upper contacts lead us to consider its age as Lopingian–Induan. The five sets of tracks studied were compared with several ichnotaxa and body fossils with appendicular elements preserved, allowing us to attribute these tracks to dicynodonts and other indeterminate therapsids. Even though the “Pirambóia Formation” track record is sparse and sub-optimally preserved, it is an important key to better understand the occupation of arid environments by tetrapods across the Permo–Triassic boundary.
... Tetrasauropus trackway configuration, however, seems to be more wide-gauge than in the studied specimens, and there are no other recognizable morphological remarks, e.g. the curved digits with distinct claw marks both in the pes and in the manus, or the entaxony of the pes. Moreover, Tetrasauropus has almost always been reported from the Late Triassic; there is only one occurrence in the Early Jurassic of this ichnotaxon (Milàn et al., 2008), but the poor preservation of the studied tracks prevents any reliable comparison. Parabrontopodus isp. ...
Dinosaur footprints from the Lower Jurassic of northeastern Italy are well known and, since the first discoveries in the early 1990s, many sites have been described. Tracks are mostly found in the peritidal limestones of the Calcari Grigi Group, deposited on the Trento carbonate platform, now cropping out in the Southern Alps. In 2011, a group of speleologists discovered a new tracksite in the Lower Jurassic Calcari Grigi Group exposed almost at the top of Mt. Pelmo (Dolomites), 3037 m above sea level. Footprints are generally poorly preserved, but it proved possible to recognise some tridactyl footprints with theropodian features (i.e., elongated digit III and narrow interdigital angle) and some possible quadruped tracks whose configuration resembles that of a sauropodomorph trackmaker. Careful examination of the depressions excludes their inorganic origin (chemical weathering). Despite the poor quality of the traces, the Pelmo site is significant because it is the most easterly site ever found on the Trento Platform and the only one which is located north of the Valsugana Fault. This fault system is a major alpine tectonic lineament that separates the classical successions of the Calcari Grigi Group in the Italian Prealps from those located in the Dolomites. Moreover, the discovery of the Pelmo tracks considerably expands the documented area of movement of Early Jurassic terrestrial vertebrates in the northern part of the Trento Platform, extending the size of the Early Jurassic megatracksites of the Southern Alps. RIASSUNTO-[Orme di dinosauro dalla cima del Mt. Pelmo: nuovi dati sulla paleogeografia del Giurassico Inferiore delle Dolomiti (NE Italia)]-Le impronte di dinosauri del Giurassico Inferiore del nordest italiano sono ben note e, dopo la prima scoperta all'inizio degli anni Novanta, sono stati riconosciuti diversi siti. Le impronte si trovano nei calcari pertitidali del Gruppo dei Calcari Grigi, depositatosi sulla piattaforma di Trento e affiorante oggi nelle Alpi Meridionali. Nel 2011, un gruppo di speleologi scoprì un nuovo sito nel Giurassico Inferiore dei Calcari Grigi, situato a 3037 m sul livello del mare, quasi alla sommità del Mt. Pelmo (Dolomiti). La qualità di conservazione delle orme è generalmente scarsa, tuttavia è possibile riconoscere alcune orme tridattile con caratteristiche teropodiane (dito III molto allungato, angolo interdigitale stretto) e alcune orme quadrupedi con una configurazione simile a quella dei sauropodi (o sauropodomorfi). L'attenta analisi delle depressioni esclude la loro origine inorganica (erosione chimica, carsismo). Nonostante la scarsa qualità delle orme, la scoperta del Pelmo è significativa perché il sito è il più orientale mai rinvenuto e l'unico situato a nord della Linea della Valsugana, un importante lineamento tettonico che separa le classiche successioni dei Calcari Grigi nelle Prealpi da quelle delle Dolomiti. Grazie al sito del Pelmo l'area dove si riscontra la presenza dei vertebrati nel Giurassico Inferiore si allarga alla parte settentrionale della Piattaforma di Trento, estendendo le dimensioni del mega-sito ad impronte del Giurassico Inferiore delle Alpi Meridionali.
... A general overview of possible synapsid tracks from similar environments should also take Navahopus into account, a quadrupedal ichnotaxon with two ichnospecies: N. falcipollex Baird (1980), and N. coyoteensis (Milan, Loope, and Bromley, 2008), both from the Lower Jurassic Navajo Sandstone of the United States. Lockley and Hunt (1995) discussed extensively on the subject, noting the similarity between Navahopus and Brasilichnium. ...
A new ichnospecies, Brasilichnium anaiti, is erected on material from the Botucatu Formation of Brazil. The general morphology supports ichnotaxonomic similarity between the new ichnotaxon and Brasilichnium elusivum Leonardi, 1981, even if a separation at the ichnospecies level is evident, based on differences in shape and arrangement of pes digit marks along with a clear dimensional gap between both ichnotaxa. Similar forms from the Lower Jurassic of the United States are known and should be included under this new ichnotaxonomic label, based on shared morphological features. B. anaiti is constantly associated with B. elusivum in dune foresets of hyperarid paleoenvironments, to which these forms are restricted. This makes B. anaiti a further element of the Brasilichnium ichnocoenosis in the larger framework of the Chelichnus ichnofacies. Re–evaluation of possible trackmakers highlights the difficulties of unequivocal referring this ichnotaxon to a specific producer, but restrains potential trackmakers to early mammaliamorph therapsids.
