Marco Avanzini

Palaeontology: Human footprints in Pleistocene volcanic ash

We have analysed three fossilized trackways of human footprints in a zeolite-rich pyroclastic flow dated to 385,000–325,000 years ago (kyr), discovered along the western margin of the Roccamonfina volcanic complex in southern Italy. We believe that these tracks are the oldest human footprints found so far and that they were made by hominids who had a fully bipedal, free-standing gait, using their hands only to steady themselves on the difficult descent.

Anatomy of a footprint: Bioturbation as a key to understanding dinosaur walk dynamics

A series of polished slabs, cut vertically through a Grallator footprint, proved to be very useful in the reconstruction of the walking dynamics of theropod dinosaurs, and to an understanding of the animal‐substrate interactions. The trampled layer comprises a succession of plastic sediments and elastic cyanobacterial laminites, capped by semiliquid carbonate mud. The sections display records of the different pressures exerted onto the substrate by variable morphologic elements of the foot. Consequently it is possible to reconstruct the way the producing dinosaur walked. A progressive shift of the center of gravity is recorded by the different function of the digits in the different movement phases. The IV digit had a dominant function during the touch‐down and the beginning of the weight‐bearing phase. The II digit appears to have played an unexpected dominant function during the whole touch‐down and weight‐bearing phase, with a marked inward tangential translation and a diagonal penetration into the sed...

Shrinking the World's Largest Dinosaur Tracks: Observations on the Ichnotaxonomy of Gigantosauropus asturiensis and Hispanosauropus hauboldi from the Upper Jurassic of Asturias, Spain

The type material of the ichnospecies Gigantosauropus asturiensis Mensink and Mertmann 1984 is re-examined and shown to represent a sauropod rather than a theropod. This interpretation confirms the recent suggestions of several authors. We describe the trackway in detail but conclude that it is not diagnostic at any taxonomic level, below the general category of sauropod. Thus, G. asturiensis may legitimately be considered a nomen dubium, and the name should be restricted to the original material and not extended to formally describe other poorly preserved specimens. Claims that the largest pes tracks are 1.35 or even 1.5 m in length are incorrect. Pes length ranges from 98–125 cm (mean 110.75 cm). Hispanosauropus hauboldi Mensink and Mertmann 1984 is also of doubtful utility as previously defined. The holotype, a field specimen, which clearly represents a theropod dinosaur, cannot be located, and may be lost to erosion. The paratype is a sauropod track and therefore has no relevance to the ichno-species description. Therefore, we select a new paralectotype and provide a more detailed description of specimens that can be assigned to this ichnotaxon. Hispanosauropus is similar to tracks recently described under the label Megalosauripus. However, the status of this latter ichnogenus, and the spectrum of track types to which it refers, is disputed. Thus, we provisionally restrict the name Hispanosauropus to the original illustrated holotype and a paralectotype from the same locality. On the grounds of morphological similarity, the name may be applied to similar material from elsewhere in the Upper Jurassic of Asturias.

Crocodylomorph Tracks from the Late Jurassic of Asturias (Spain)

Some small and medium-sized crocodylomorph footprints are described from the Late Jurassic (Kimmeridgian) coastal and deltaic units of the northern Spain (Asturias). There are at least four footprint morphotypes. Three of them, with well preserved trackways, are included in the ichnogenus Crocodylopodus (Crocodylopodus isp. and Crocodylopodus meijidei); the fourth one, documented by some isolated large footprints, is referable to the ichnogenus Hatcherichnus. This ichnoassociation confirms the presence of small crocodilians in palaeoenvironments apparently dominated by dinosaurs. The presence of Hatcherichnus seems to confirm the affinity between the Iberian and North American ichnofaunas.

Lavinipes Cheminii Ichnogen., Ichnosp. nov., A Possible Sauropodomorph Track from the Lower Jurassic of the Italian Alps

A new ichnotaxon is described from the Lower Jurassic (Upper Hettangian-Lower Sinemurian) carbonate tidal flats on the central-eastern Italian Alps. The narrow-gauge trackway is that of a large quadrupedal dinosaur. The pes is functionally tetradactyl with three rounded antero-medially directed digits, and the manus is pentadactyl. This quadrupedal form is close to Otozoum and Pseudotetrasauropus jaquesi both traditionally related to sauropodomorph trackmakers. The similarity with Otozoum is so marked that Lavinipes and Otozoum could be cogeneric. But the overall evidence today is that the Otozoum trackmaker was generally bipedal, whereas the trackmaker of L. cheminii is fully quadrupedal. The manual prints of L. cheminii show five short clawless digits and are different from the tetradactyl slender toed manual prints of Otozoum. The possible sauropodomorph affinity of the L. cheminii trackmaker is here discussed with an attempt to a revision of the Late Triassic-Jurassic tracks which have been traditionally related to sauropod and prosauropod.

Middle Triassic archosaur population structure: interpretation based on Isochirotherium delicatum fossil footprints (Southern Alps, Italy)

Abstract Well-preserved archosaur footprints have recently been found on a single bedding plane in the Italian Alps. The tracks are referable to Isochirotherium delicatum Courel and Demathieu 1976, a form that was identified for the first time at the Anisian–Ladinian boundary in the area of Argentiere (Ardeche, France). The Isochirotherium delicatum footprints and trackways from Gampenpass represent a possible social group or ‘herd’. Estimating the age of the trackmakers from the examination of the footprints is difficult and complicated by the fact that the sample can be divided into two groups of tracks (distinguishable by the L / W , cross axis and interdigital angle). The diversity of the tracks is here interpreted as an indication of sexual dimorphism.

The Devil's Trails: Middle Pleistocene Human Footprints Preserved in a Volcanoclastic Deposit of Southern Italy

Three fossilized trackways of human footprints were discovered in a pyroclastic flow dated to 385–325 ka, along the western margin of the Roccamonfina volcanic complex in Southern Italy. The pyroclastic flow is zeolite-rich and was probably emplaced at a relatively low temperature, forming a nonwelded pyroclastic deposit. The well-preserved footprints show the interesting strategies used by ancient humans in descending steep slopes. The footprints, short and very broad, are entaxonic, plantigrade, with an average length of 24cm and an average width of 10 cm. The three trackways are narrow with an oblique pace of about 60 cm and a stride of about 120 cm. If dating constraints are correct, the Roccamonfina human fossil footprints are the oldest known in Europe and among the oldest in the world. Moreover, they are preserved on a steep slope lying in a subaerial setting and are associated with handprints. For their potential in preserving evidence of behavior, these tracks provide unique insight into the activities of some of the earliest known Europeans.

A Tetrapod Ichnoassociation from the Middle Triassic (Anisian, Pelsonian) of Northern Italy

A new Middle Triassic ichnofauna recovered nearby the town of Tisens (Bozen) in the Adige Valley (Trentino, Northern Italy) is described. A relatively large ichnoassociation, in which various ichnogenera can be recognized, comes from the basal inter-supratidal layers of a mixed carbonate siliciclastic unit of Pelsonian (Middle Anisian) age. Most of the isolated footprints and trackways pertain to lizard-like reptiles referable to Rhyncosauroides and, subordinately, to archosaurian reptiles. In particular, the ichnogenera Rotodactylus, Synaptichnium and Chirotherium have been recognized. Many tracks are at present unidentified; among them a lizard-like morphotype (morphotype A). The site also yelded numerous fossil plant horizons and some scattered vertebrate remains referable to Placodontidae (cf. Placodus gigas). The site shows the continuity in the Pelsonian of the “chirothere ichnofauna” and the dominance of Rhynchosauroides in carbonate, tidal flat environments.

Synaptichnium tracks with skin impressions from the Anisian (middle Triassic) of the Southern alps (val di non ‐ Italy)

In Val di Non (northern Italy), siltstones of Anisian age (middle Triassic) yield archosaurian and other reptilian tracks which show excellent details of their scaly plantar and palmar surfaces. The ichnofauna includes Rhynchosauroides, Chirotherium, Brachichiroth‐erium, Isochirotherium and Synaptichnium as well as tracks which can be ascribed to procolophonid reptiles and arthropod trails. The excellent preservation of scale imprints shows that the epidermal morphology of Synaptichnium differs from that of chirotheriids, and bears similarities to the lepidosauria. This observation is further proof of the primitive character of “chiroth‐eriid”; Synaptichnium, which is evident from both the pes anatomy and skin cover. Therefore the discovery of well‐preserved skin imprints at Gampenpass poses the question whether the classification of the ichnoge‐nus Synaptichnium should be revised.

Hyloidichnus bifurcatus Gilmore, 1927 and Limnopus heterodactylus (King, 1845) from the Early Permian of Southern Alps (N Italy): A New Equilibrium in the Ichnofauna

Studies on Early Permian tetrapod ichnofauna emphasized the scarcity of forms from Italian sites. A revision work on the entire collections revealed the presence of Hyloidichnus bifurcatus Gilmore, 1927 and Limnopus heterodactylus (King, 1845). The ichnoassociation now lists seven ichnogenera: Amphisauropus, Batrachichnus, Dromopus, Erpetopus, Hyloidichnus, Limnopus, Varanopus. These new data enlarge the ichnoceonosis, adding tracks of medium-size captorhinomorphs (Hyloidichnus) and temnospondyls (Limnopus) to the Italian ichnofauna, previously characterized by scarcity of predators and amphibians. Radiometric ages give a strong age constraint to the ichnoassociation (Early Kungurian), allowing useful correlations to contemporary successions all over the world. The main difference is the absence of Ichniotherium and Dimetropus, and this could have a stratigraphic or paleoenvironmental significance. The fauna is similar in two main basins, Collio and Orobic. It differs solely in the proportions between ichnotaxa, with a predominance of areoscelid traces (Dromopus) in the Collio Basin and of captorhinomorph traces (Erpetopus, Varanopus, Hyloidichnus) in the Orobic Basin. This datum could reflect slightly different environments, seasonal in the Collio Basin (alluvial plain) and more arid in the Orobic Basin (playa-like). The lack of some forms in smaller basins of the Athesian Volcanic Complex is probably due to a bias.