Paleoichnology

Nuevas huellas terópodas en el Yacimiento 4 AM en Aït Mimoun (Sinclinal de Iouaridène, Alto Atlas, Marruecos)

by Ignacio Díaz-Martínez

Díaz-Martínez, I., Ladel, L., Martín, D., Saasanik, S., Buzzi, J., Ghadbane, S., Luján, A. H.,Moussa, D., Martínez, V., Elazzouzi, Y. & García-Ortiz de Landaluce, E. 2009. Nuevas huellas terópodas en el yacimiento 4Am en Aït Mimoun (Sinclinal de Iouaridène, Alto Atlas, Marruecos). Paleolusitana, 1: 151-159. (In Spanish).

ABSTRACT
In the Iouaridène Syncline (High Atlas, Morocco) 28 sites have been studied, with 781 dinosaur... more ABSTRACT
In the Iouaridène Syncline (High Atlas, Morocco) 28 sites have been studied, with 781 dinosaur footprints listed. The theropod tracks are the most abundant in the area. The sites are located in the red layers of the Iouaridène Formation of Oxfordian-Kimmeridgian age (Upper Jurassic).
Two trackways and a pair of theropod footprints have been found in the 4am site next to the sauropod trackway where the ichnospecies Breviparopus taghbaloutensis was defined.
The pair 4Am6 consists of 2 theropod tracks of more than 40 cm long. The 4Am7 trackway consists of a sequence of 9 small theropod footprints (24 cm in length). 4Am8 is a trackway of about 25 m long with 17 large tracks (42 cm long on average) out of a total of 24.
All tracks are true footprints and were formed after the mud cracks. None of the tracks can be considered as an undertrack.

Keywords: Paeoichnolgy, theropod footprints, dinosaur, Iouaridène Syncline, Morocco

Nuevas aportaciones al registro paleoicnológico en Cabezón de Cameros (La Rioja. España)

by Esperanza García Ortiz de Landaluce

Dinosaurs, footprints, Lower Cretaceous, Cuenca de Cameros, Spain.

Cabezon de Cameros is a well known place for paleoichnological workers because one of the first described iguanodontid... more Cabezon de Cameros is a well known place for paleoichnological workers because one of the first described iguanodontid cuadrupedal trakways was found there. Up to now, this was the only site known in this place. In this paper we describe five new sites found near the one mentioned above. They not only widen the paleoichnological record of the region, but also give new interesting data about the kind and distribution of dinosaurs and the ichnological record of Cameros Basin lithoestratigraphical groups.

Nuevas huellas terópodas en el yacimiento 4AM de Ait Mimoum (Marruecos, Alto Atlas)

by Esperanza García Ortiz de Landaluce

Paeoichnolgy, theropod footprints, dinosaur, Iouaridène Syncline, Morocco

In the Iouaridène Syncline (High Atlas, Morocco) 28 sites have been studied, with 781 dinosaur footprints listed. The... more In the Iouaridène Syncline (High Atlas, Morocco) 28 sites have been studied, with 781 dinosaur footprints listed. The theropod tracks are the most abundant in the area. The sites are located in the red layers of the Iouaridène Formation of Oxfordian-Kimmeridgian age (Upper Jurassic).
Two trackways and a pair of theropod footprints have been found in the 4am site next to the sauropod trackway where the ichnospecies Breviparopus taghbaloutensis was defined.
The pair 4Am6 consists of 2 theropod tracks of more than 40 cm long. The 4Am7 trackway consists of a sequence of 9 small theropod footprints (24 cm in length). 4Am8 is a trackway of about 25 m long with 17 large tracks (42 cm long on average) out of a total of 24.
All tracks are true footprints and were formed after the mud cracks. None of the tracks can be considered as an undertrack.

Evidence of an Early Triassic age (Olenekian) in Argana Basin (High Atlas, Morocco) based on new chirotherioid traces

by J.Sébastien Steyer

New Permian tetrapod footprints and macroflora from Turkey (Cakraz Formation, northwestern Anatolia): Biostratigraphic and palaeoenvironmental implications

by J.Sébastien Steyer

Timing of Post-Glacial Reinhabitation and Ecological Development of Two New England, USA, Drainages Based on Trace Fossil Evidence

by Jacob Benner

http://dx.doi.org/10.1016/j.palaeo.2008.10.029

Trace fossils as paleoecological and paleobiogeographical tools in Pleistocene glaciolacustrine sediments have been... more Trace fossils as paleoecological and paleobiogeographical tools in Pleistocene glaciolacustrine sediments have been largely ignored. Combining high resolution varve stratigraphy with trace fossil data can lead to refined paleoenvironmental interpretations during times of rapid climate change. Based on trace fossils from glaciolacustrine varves in the Connecticut and Merrimack River valleys, a new timeline for the reinhabitation of New England by fish and associated invertebrates has been constructed. In addition, it appears that colonization of the recently deglaciated environments occurred in at least four successional stages. If these stages can be recognized elsewhere, it may be possible to accurately model other postglacial migrations using trace fossils and varve chronostratigraphy.

Late Carboniferous paleoichnology reveals the oldest full-body impression of a flying insect

by Jacob Benner

Co-authored with Richard J. Knecht and Michael S. Engel

Insects were the first animals to evolve powered flight and did so perhaps 90 million years before the first flight... more Insects were the first animals to evolve powered flight and did so perhaps 90 million years before the first flight among vertebrates. However, the earliest fossil record of flying insect lineages (Pterygota) is poor, with scant indirect evidence from the Devonian and a nearly complete dearth of material from the Early Carboniferous. By the Late Carboniferous a diversity of flying lineages is known, mostly from isolated wings but without true insights into the paleoethology of these taxa. Here, we report evidence of a full-body impression of a flying insect from the Late Carboniferous Wamsutta Formation of Massachusetts, representing the oldest trace fossil of Pterygota. Through ethological and morphological analysis, the trace fossil provides evidence that its maker was a flying insect and probably was representative of a stem-group lineage of mayflies. The nature of this current full-body impression somewhat blurs distinctions between the systematics of traces and trace makers, thus adding to the debate surrounding ichnotaxonomy for traces with well-associated trace makers.

Gyrolithes as a multipurpose burrow: an ethologic approach

by Renata Netto

Co-authored with Luis A. Buatois, María Gabriela Mángano and Patricia Balistieri. Published at Revista Brasileira de Paleontologia, volume 10, issue 3, pages 157-168.

Spiral burrows perpendicular to the bedding plane are well known in the fossil record and are usually referred to the... more Spiral burrows perpendicular to the bedding plane are well known in the fossil record and are usually referred to the ichnogenus Gyrolithes. Common in Mesozoic and Cenozoic marginal-marine, brackish-water deposits, the only records of Gyrolithes in Paleozoic rocks are from the Cambrian. In Permian rocks of the Paraná Basin (Rio do Sul and marine, brackish-water siltstone and mudstone, closely associated with Thalassinoides, forming a Glossifungites suite. with extreme salinity fluctuations in Mesozoic and Cenozoic brackish-water environments. However, spirals produced by strategy to exploit organic-rich zones of the substrate in calm and protected environments. The discovery of spiral burrows in Permian marginal-marine stiffgrounds to firmgrounds indicates that this strategy was already adopted by some group of infaunal crustaceans in brackish-water ecosystems during the late Paleozoic.

Laboratory Controlled Simulations of Dinosaur Footprints in Sand: a Key to Understanding Vertebrate Track Formation and Preservation

by Simon Jackson

Co-authored with: Martin A Whyte, Mike Romano

Dinosaur tracks and trackways yield invaluable information as to the identity, size, and gait of the trackmaker and... more Dinosaur tracks and trackways yield invaluable information as to the identity, size, and gait of the trackmaker and the conditions of the media (=substrate) it traversed. Correctly interpreting tracks requires consideration of their three-dimensional morphology. Laboratory-controlled simulations were conducted to investigate the subsurface track morphology formed from differently shaped feet, as the shape of the footprint deteriorates with depth. A circular, triangular, and a tridactyl dinosaur foot-shaped template, or indenter, were indented vertically into two types of sand, with four moisture contents—dry, 10%, 20%, and saturated. The morphology of all three indenters was preserved most accurately in the moist sand. Tracks in dry and saturated sand were distorted by a greater degree of media deformation. Digit imprints of tridactyl tracks were only clearly discernible in near-surface layers and were deformed by shear zones or inward movement of sediment in dry and saturated sand. The long digits of the template produced the greatest degree of outward displacement, and tracks became wider with depth and deepest in the heel region. This was most distinct in dry sand, where extensive shear zones in cross section demonstrated the outward and upward movement of sediment. All tracks in saturated sand were characterized by considerable downward displacement of sediment and features related to the upward pull of sediment as the templates were withdrawn. These diagnostic features allow vertebrate tracks to be differentiated from nonbiogenic, soft-sediment deformation. Fossil tracks studied from the Middle Jurassic succession of the Cleveland Basin, Yorkshire, demonstrate affinities to the experimental tracks formed in saturated sand.

Range of Experimental Dinosaur (Hypsilophodon foxii) Footprints Due to Variation in Sand Consistency: How Wet Was the Track?

by Simon Jackson

Co-authored with Martin A Whyte, Mike Romano

The laboratory-controlled simulations of dinosaur footprints in this study revealed characteristic track features that... more The laboratory-controlled simulations of dinosaur footprints in this study revealed characteristic track features that could be used to identify the consistency of sand substrates and provide an insight into the paleoenvironment. A model foot of Hypsilophodon foxii was indented into three sands of four different moisture (= water) contents. The two intermediate moist states were characterized by shallow tridactyl impressions, in which only digits II-IV were impressed, showing details of padding and claws. Where the foot penetrated more deeply, in the dry and saturated states, the hallux and heel were also impressed; in these cases, the foot detail was not preserved accurately and track morphology deviated significantly from that of the foot. Dry sand tracks were characterized by the outward and upward movement of sediment and tracks in saturated sand by mainly downward displacement. The finer-grained saturated sand was also associated with liquefaction and closure of digit imprints. Tracks from the Middle Jurassic Cleveland Basin of Yorkshire showed features of the saturated state. The range of experimental track morphotypes formed by one foot highlighted the difficulties in assigning a print type to a particular trackmaker and the importance of excluding preservational variants from ichnotaxonomic studies.

Trackway Ratio: A New Look at Trackway Gauge in the

by Simon Jackson

Authors: M Romano, MA Whyte, SJ Jackson (University of Sheffield, Dinosaur Track Research Group)

A new parameter, the Trackway Ratio (TR), is proposed to supplement the previously used trackway gauge to describe and... more A new parameter, the Trackway Ratio (TR), is proposed to supplement the previously used trackway gauge to describe and quantify the relative width of trackways in dinosaur quadrupedal gaits. It is expressed as the ratio of the width of the tracks relative to the total width of the trackway (both measured perpendicular to the long axis of the trackway). The ratio may be used with either pes (PTR) or manus (MTR) tracks. The PTR range of values for wide-, medium- and narrow-gauge trackways of previous authors are provisionally suggested to be ≤35%, 36-49% and ≥50%, respectively. The application of such a ratio would permit a more consistent ichnotaxonomy to be adopted where both track morphology and trackway parameters are used to define ichnotaxa. Determination of the TR, as well as other parameters, will be affected by track preservation quality. Recent experiments on track simulation in the laboratory have shed further light on observations made in the field concerning the value of track measurements (in particular track length and width) recorded from below the surface on which the maker was moving. Experimental track simulations in the laboratory have shown that the dimensions of transmitted tracks preserved below the surface on which the foot was impressed may vary from 65% to 135% of the true dimensions of the indenter. Two case studies are presented that quantify the errors that may be made on calculating TR and the size, gait and speed of the maker, from trackways if the preservation of the tracks are not fully understood. It is shown that in individual trackways the PTR may vary along the length of the trackway; so that part of the trackway may be classified as wide-gauge and other parts medium-gauge. There is a relationship between variation in PTR and that of pace angulation along the length of a single trackway. An analysis of 42 trackways, principally sauropod, shows a temporal distribution that does not agree closely with previous suggestions relating to narrow- and wide-gauge trackways