TRACE FOSSILS FROM THE PERMIAN TERESINA FORMATION AT CERRO CAVEIRAS (S BRAZIL)
by Renata Netto
Co-authored with João Henrique Dobler Lima (first author), published in Revista Brasileira de Paleontologia, 2012. This paper was a contribution to the First Symposium on Latin American Ichnology - SLIC 2010.
The ichnofauna of the Teresina Formation from the Cerro Caveiras (Dom Pedrito, Rio Grande do Sul State, South Brazil)... more
The ichnofauna of the Teresina Formation from the Cerro Caveiras (Dom Pedrito, Rio Grande do Sul State, South Brazil) is revised in this paper. Bergaueria isp., Cochlichnus cf. anguineus, Cruziana problematica, cf. Diplocraterion
isp., Diplopodichnus biformis, Helminthopsis isp., Lockeia siliquaria, Multina arcuata isp. nov., Oldhamia isp., Palaeophycus striatus, P. tubularis, Phymatoderma burkei, Planolites beverleyensis, P. montanus, Teichichnus isp., and Thalassinoides isp. were recorded. Isopodichnus problematicus, Helminthopsis tenuis and Unarites isp., previously described in these deposits are now described as Cruziana problematica, indeterminate molluscan trail, and Multina arcuata isp. nov., respectively. The ichnofauna is composed chiefly of horizontal, simple shallow burrows, with a predominance of feeding structures. Resting, dwelling and crawling structures also occur, as well as indeterminate tiny grazing trails, but are less frequent. Ichnodiversity and intensity of bioturbation are usually low, and P. montanus is the commonest ichnotaxon. The main characteristics of the ichnofauna suggest a marine benthic fauna stressed by salinity fluctuations and resulting in an impoverished Cruziana ichnofacies. The absence of vertical burrows and the common occurrences of monospecific assemblages of Planolites indicate extreme stress events, probably due to the establishment of freshwater conditions. Further studies focused on the ichnological signatures of these deposits will provide more detailed information to improve the current paleoecologic and paleoenvironmental interpretations of the Teresina Formation deposits.
Download (.pdf) Clavate borings in a Miocene cetacean skeleton from Tarragona (NE Spain) and the fossil record of marine bone bioerosion
Belaústegui, Z., Gibert, J.M. de, Domènech, R., Muñiz, F., Martinell, J. 2012. Palaeogeography, Palaeoclimatology, Palaeoecology, 323–325, 68–74.
Clavate borings found in the tympanic bulla of a Miocene cetacean from El Camp de Tarragona Basin constitute the first... more Clavate borings found in the tympanic bulla of a Miocene cetacean from El Camp de Tarragona Basin constitute the first evidence of the ichnogenus Gastrochaenolites in bones of an autochthonous cetacean carcass. Previous records of similar trace fossils on marine bones were described from transported or reworked remains. Based on their morphology and ichnotaxonomy, the borings are assigned to the activity of pholadid bivalves, which would have colonized the skeletal carcass on the sea floor after removal of covering soft tissues. Sedimentological and paleontological data indicate a low-energy depositional setting with low sedimentation rate, which would have provided the temporal window for bivalve colonization. This new finding contributes to widen our knowledge of bioerosion in marine vertebrate skeletons.
Paleohydrological significance of trace fossil distribution in Oligocene fluvial-fan-to-lacustrine systems of the Ebro Basin, Spain
Gibert, J.M. de; Sáez, A. 2009. Palaeogeography, Palaeoclimatology, Palaeoecology, 272(3-4): 162-175
The ichnological study of fluvial fan and lacustrine Oligocene deposits in the NE Ebro Basin has allowed the... more The ichnological study of fluvial fan and lacustrine Oligocene deposits in the NE Ebro Basin has allowed the recognition of three ichnoassemblages having a strong correlation with depositional facies associations. Lacustrine deposits lack bioturbation due to the hydrologically closed character of the lake that caused hypersalinity and made it inhospitable for benthic life. Terminal lobe deposits of the fluvial fan, which were sedimented in low wetland areas around the lake, bear a moderately diverse ichnoassemblage dominated by horizontal Taenidium barretti, Cochlichnus anguineus and bird footprints (Gruipeda isp.). This assemblage can be assigned to the 'shorebird ichnofacies', a subset of the Scoyenia ichnofacies that characterizes the subaerial part of low-energy shore areas. Crevasse splay deposits in medial fluvial fan areas present a different assemblage also belonging to the Scoyenia ichnofacies. It includes most of the trace fossils found in the terminal lobes, except for the bird tracks, plus very abundant vertical burrows (Taenidium barretti and unnamed ornamented burrows). The presence of deep-tier traces of terrestrial invertebrates is consistent with the more proximal fan setting, having greater relief and consequently a lower mean groundwater position than lowland areas. Fluvial channels only bear irregularly clustered tunnel structures of unknown affinity formed after abandonment of the channel. Thus, trace fossil assemblages are mostly controlled by the position and fluctuations of water tables, which are the cause for their composite nature.
Paleobiology of the crustacean trace fossil Spongeliomorpha iberica in the Miocene of southeastern Spain
Gibert, J.M. de; Ekdale, A.A. 2010. Acta Palaeontologica Polonica 55 (4), 733-740.
The trace fossil Spongeliomorpha iberica locally occurs in the Tortonian (Upper Miocene) marine strata of the Fortuna... more The trace fossil Spongeliomorpha iberica locally occurs in the Tortonian (Upper Miocene) marine strata of the Fortuna basin in southeastern Spain, and its excellent preservation state allows a reliable reconstruction of its main morphologic features. The burrow systems are branched (but not anastomosing), and they include numerous, short, blind tunnels. The burrow walls are strongly ornamented with bioglyphs displaying a rhomboidal pattern, consisting mostly of individual “Y”-shaped scratches. Smaller, secondary bioglyphs consist of sets of less incised transverse scratches. These features allow us to assign the ichnospecies to a decapod crustacean, most likely an alpheid or thalassinidean shrimp. The burrow apparently served as a refuge for the inhabitant, which fed upon microorganisms growing on the walls of the burrow by means of scraping the interior surfaces with the maxillipeds or other mouth parts. It is also likely that the shrimp used the multiple blind tunnels to store organic material (probably plant detritus) to be used for later consumption. The crustaceans colonized mud firmgrounds, which were formed by erosion during a rapid sea-level fall. Thus, the burrows occur in direct association with erosional regressive surfaces and therefore are good stratigraphic indicators of abrupt paleoenvironmental change.
Reinterpretation of Climactichnites Logan 1860 to include subsurface burrows, and erection of Musculopodus for resting traces of the trailmaker
Full refeerence:
Getty, P. R. and Hagadorn, J. W. 2008. Reinterpretation of Climactichnites Logan 1860 to include subsurface burrows, and erection of Musculopodus for resting traces of the tracemaker. Journal of Paleontology, 82:1161-1172.
Producing and preserving Climactichnites
Full reference:
Getty, P.R. and Hagadorn, J.W. 2006. Producing and Preserving Climactichnites. Geological Society of America Abstracts with Programs, Vol. 38, No. 7, p. 475.
Most Climactichnites represent epifaunal trackways of an unknown, soft-bodied, Late Cambrian animal. Infaunal burrows... more
Most Climactichnites represent epifaunal trackways of an unknown, soft-bodied, Late Cambrian animal. Infaunal burrows made by the Climactichnites trackmaker are similar, but often better preserved. They exhibit fine striations atop transverse bars, lack lateral ridges, and like many Cruziana and Rusophycus, are preserved by overlying sediment sealing them from erosion. Modern gastropods, including Bullia digitalis and Polinices duplicatus make subaqueous and subaerial trackways similar to epifaunal Climactichnites and are the best analogue for understanding Climactichnites production and preservation.
To test the hypothesis that epifaunal Climactichnites were preserved by mucus, experiments using the aquatic gastropod Viviparus intertextus were conducted. Although copious amounts of mucus were secreted, it was insufficient to preserve Viviparus trackways. When trackways were submerged, mucus floated to the surface and agitation by waves mobilized the surrounding sand, thus undermining the trackway. Field observations of intertidal gastropods support experimental observations; agitation of sand by waves mobilizes the bed surface and completely obliterates trackways. In the Late Cambrian Elk Mound Group of Wisconsin, delicate arthropod trackways occur on the same medium-coarse grained bed surfaces as Climactichnites; these are not undertracks nor are they produced by mucus-secreting animals. Thus, other non-mucus mechanisms must be responsible for the preservation of Climactichnites surface traces. Rapid burial can be rejected because many traces are blanketed by fine-grained beds deposited under low-energy hydraulic regimes. Even more perplexing are coarse sand beds and tidal channels directly above Climactichnites trackways that are not eroded. Together, these suggest an alternative preservational hypothesis: microbial biofilms stabilized track surfaces on which many epifaunal Climactichnites were made. In support of this hypothesis, microbial sedimentary structures, such as domal sand buildups (i.e., sand stromatolites), are cross-cut by, and grow over some epifaunal Climactichnites trackways, and elsewhere in studied sections, other microbial structures are common.
Small Climactichnites trackways: Their abundance and implications for trackmaker physiology
Full reference:
Getty, P. R. and Hagadorn, J.W. 2005. Small Climactichnites trackways: their abundance and implications for trackmaker physiology. Geological Society of America Abstracts with Programs, Vol. 37, No. 7, p. 486.
Climactichnites wilsoni is the trackway of an unknown, soft-bodied late Cambrian animal that inhabited marginal marine... more
Climactichnites wilsoni is the trackway of an unknown, soft-bodied late Cambrian animal that inhabited marginal marine settings and might have been among the first animals to venture onto land. The width of these trackways (4- 30 cm) is directly related to the size of the trackmaker. The smallest reported trackways are 4- 8 cm wide and are restricted to one quarry in Wisconsin. It has been suggested that small trackways are rare because the animals were unable to compact the wet sand on which larger trackways are preserved, or that a high rate of predation by arthropods (such as those that produced Protichnites) limited the number of potential small trackmakers.
Here we report on small Climactichnites (~2-3 cm wide) that occur in Québec, New York, Wisconsin, and Missouri. These trackways sometimes occur in abundance on bedding planes, indicating that large numbers of the animal inhabited some localities. The trackways exhibit variable morphologies ranging from those with lateral ridges, transverse bars, and furrows to those missing one or more of these features. Variable morphologies are sometimes exhibited by trackways on the same slab. This variability is interpreted to result from differences in trackmaker behavior, sediment rheology, taphonomy, and/or fossil collection approaches. The trackways occur on fine- to medium-grained sandstones, some of which have intercalcated coarse grains. In some cases the trackways crosscut and modify oscillation ripples, indicating that these small animals were able to modify relatively large sedimentary structures during track formation.
Together, these trackways are important because they demonstrate that small, possibly juvenile Climactichnites-producing animals were abundant and geographically widespread, and that they had the physiological capacity to manipulate sediment to produce trackways like those of larger trackmakers.
Palaeobiology of the Climactichnites tracemaker
Full reference:
Getty, P. R. and Hagadorn, J. W. 2009. Paleobiology of the Climactichnites tracemaker. Palaeontology, 52:753-778.
TRACKWAYS OF MODERN BASAL INSECTS (JUMPING BRISTLETAILS AND SILVERFISH) AND THE ORIGIN OF PENNSYLVANIAN ARTHROPOD TRACE …
Full reference:
Getty, P.R., Sproule, R., Wagner, D. and Bush, A.M. 2009. Trackways of modern basal insects (jumping bristletails and silverfish) and the origin of Pennsylvanian arthropod trace fossils from eastern Massachusetts. Geological Society of America Abstracts with Programs, Vol. 41, No. 7, p. 161.
A quarry in Plainville, MA is the source of arthropod traces from the Pennsylvanian-aged Rhode Island Formation,... more A quarry in Plainville, MA is the source of arthropod traces from the Pennsylvanian-aged Rhode Island Formation, including the body impression Tonganoxichnus buildexensis, which is attributed to a basal, wingless insect (a monuran or jumping bristletail), as well as trackways tentatively referred to Stiaria isp. The trackways consist of alternating sets of two to three foot impressions oriented at an angle to the trackway midline, and a median impression consisting of single, double, or triple drag marks. The alternating sets of three foot impressions and the co-occurrence of T. buildexensis suggest a monuran or related insect lineage might have made the trackways. To test this hypothesis, experimental trackways were produced by wingless insects of the orders Archaeognatha (jumping bristletails; Pedetontus saltator) and Thysanura (silverfish; Thermobia domestica) on smoked glass and in mud. Both P. saltator and T. domestica produced trackways with alternating sets of two to three footprints. However, T. domestica typically produced only a single median impression as a consequence of dragging the medial terminal filament along the substrate; rarely, double or triple median grooves were produced, but they were intermittent and did not resemble the fossils. P. saltator often produced multiple median impressions as the terminal filament, lateral cerci (paired posterior appendages), and/or styli (paired abdominal appendages) dragged along the substrate. For example, a double median impression was produced by the styli, and triple median impressions were produced when the terminal filament and lateral cerci dragged along the substrate. The experimental trackways indicate that bristletails can account for all of the trackway morphologies seen in the fossils. The extinct monurans, which were anatomically similar to jumping bristletails in many respects, remain candidates for having made the fossil tracks. Silverfish similar to T. domestica could have produced trackways with single median drag marks, but the full suite of Pennsylvanian traces cannot be attributed to these derived silverfish. However, less derived silverfish (e.g., Tricholepidion gertschi, the relict silverfish) are also anatomically similar to bristletails and thus cannot be ruled out as trackmakers without further experimentation.
AN EARLY JURASSIC NON-MARINE FOSSIL ASSEMBLAGE FROM THE PORTLAND FORMATION, HARTFORD BASIN, MASSACHUSETTS
Full reference:
Collette, J.H., GETTY, P.R., and Hagadorn, J.W. 2006. A Jurassic Non-marine Fossil Assemblage from the Portland Formation, Hartford Basin, Massachusetts. Geological Society of America Abstracts with Programs, Vol. 38, No. 7, p. 68.
The Lower Jurassic sandstones of the Hartford Basin are well known for their dinosaur trackways, but few studies have... more
The Lower Jurassic sandstones of the Hartford Basin are well known for their dinosaur trackways, but few studies have addressed the invertebrate faunas found there. To begin to develop a more complete understanding of the ecology of these track-rich environments, a suite of invertebrate and vertebrate trace fossils from the Portland Formation in the Hoover Quarry, East Longmeadow, MA was examined. Formerly known as the Hines Quarry, it is notable for being one of few sites where vertebrate skeletal material has been collected in the region, including the type specimen of Stegomosuchus longipes, a small herbivorous plated reptile.
Trace fossils occur as concave and convex hyporelief and epirelief, on bed soles and surfaces, in fine arenaceous to argillaceous red sandstone. Invertebrate ichnogenera include Palaeophycus cf. tubularis, Planolites isp., Scoyenia cf. gracilis, and Skolithos isp., as well as a 75cm long, 2-3cm wide meandering to sinusoidal trace. Two other problematic trace fossils also occur, including a set of small (<1cm diameter) stellate traces and a Skolithos-like vertical burrow terminated with an unusual pattern of overlapping scratches in varying orientations. Vertebrate traces include theropod dinosaur footprints referable to Eubrontes. The type specimen of S. longipes displays a similar Skolithos-dominated assemblage on its upper and lower surface; however, the burrows do not seem to penetrate to the horizon containing the skeletal remains.
Polygonal desiccation cracks, mud curls, clay drapes, and asymmetric ripples on trace-bearing surfaces are consistent with deposition in a shallow aquatic environment that was periodically emergent. Viewed in the context of previously studied nearby sections of the Portland Formation, Hoover Quarry exposures could have been deposited in a playa, shallow lacustrine or fluvial environment. Hoover traces are typical of the Scoyenia ichnofacies, which is common in continental firmground environments.
Insights into an Early Jurassic dinosaur habitat: ichnofacies and enigmatic structures from the Portland Formation, Hoover Quarry, Massachusetts, USA
Full reference:
Collette, J. H., GETTY, P. R., and Hagadorn, J. W. 2011. Insights into an Early Jurassic dinosaur habitat: ichnofacies and enigmatic structures from the Portland Formation, Hoover Quarry, Massachusetts, U.S.A. Atlantic Geology, 47:81-98. doi:10.4138/atlgeol.2011.03
Jurassic sandstones of the Hartford basin are well known for their dinosaur trackways, but few studies have... more Jurassic sandstones of the Hartford basin are well known for their dinosaur trackways, but few studies have characterized their invertebrate ichnofaunas. A notable Portland Formation exposure in this area is the Hoover Quarry in East Longmeadow, Massachusetts, where vertebrate skeletal material (the type specimen of the crocodilian Stegomosuchus longipes) occurs in association with a diverse ichnofauna. Hoover Quarry ichnogenera include Eubrontes cf. gracilis, Planolites beverleyensis, Planolites montanus, probable Scoyenia burrows, and Skolithos isp. Also preserved at the site is Palaeophycus tortuosus, a sinusoidal burrow that had been previously synonymized with Palaeophycus tubularis. A probable Skolithos burrow termination with an unusual pattern of scratches also occurs, along with several problematic stellate structures. At this site, primary sedimentary structures on trace bearing surfaces are consistent with deposition in a shallow aquatic environment that was periodically emergent. Viewed in the context of nearby sections of the Portland Formation, Hoover Quarry exposures could have been deposited in fluvial, ephemeral lacustrine, or playa environments. Traces in the Hoover Quarry indicate a Scoyenia-Skolithos-composite ichnofacies, elements of which are commonly produced in continental firmground environments.
Prod traces (Selenichnites) from the middle Cambrian of Morocco, with hypotheses on the ethology of the tracemaker(s)
by Stacey Gibb
Stacey Gibb, Brian D.E. Chatterton & S. George Pemberton. 2011. Ichnos, 18:156-165
Workshop on Crustacean Bioturbation – Fossil and Recent, Fieldtrip Guidebook
Muñiz, F., Gibert, J.M. de, Mayoral, E. & Belaústegui, Z. 2010. Universidad de Huelva, 46 pp.
Fiedtrip guidebook concerning fossil (Neogene) and modern crustacean burrow localities in the surroundings of Lepe, SW... more Fiedtrip guidebook concerning fossil (Neogene) and modern crustacean burrow localities in the surroundings of Lepe, SW Spain.
Meyer, Ch. A. 2011. Amazing graze – Grazing traces of sea urchins on turtles – An example from the Late Jurassic of Switzerland.
Ann. Naturhist. Mus. Wien 113, 555-565.
Carapaces of marine turtles from the Late Jurassic Solothurn Turtle Limestone (Reuchenette Formation, Late... more Carapaces of marine turtles from the Late Jurassic Solothurn Turtle Limestone (Reuchenette Formation, Late Kimmeridgian) commonly yield rounded pits that may have resulted from epibi- onts or ectoparasites, although a conclusive interpretation has not yet been presented. Out of a large collection, only very few specimens of carapaces display areas that are more or less densely covered by stellate v-shaped grooves. These are attributed to the ichnotaxon Gnathichnus pentax BroMley and are interpreted as gnawing and rasping traces of the teeth of hemicidaroid sea ur- chins. The size of the traces suggests that Hemicidaris mitra (AgAssiz) which is a very frequent and autochthonous part of the fauna was the producer of these stellate grooves. The grazing traces suggest the presence of a post-mortem dense algal cover and indicate an extended exposure time of the carapaces at the sediment-water interface
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Rusophycus carleyi (James, 1885), Trace fossils from the Lower Ordovician of southern Morocco, and the trilobites that made them
by Stacey Gibb
Stacey Gibb, Brian D. E. Chatterton, and Murray K. Gingras. 2010. Ichnos, 17:271–283.
Sedimentology, taphonomy, and ichnology of Late Jurassic dinosaur tracks from the Jura carbonate platform (Chevenez—Combe Ronde tracksite, NW Switzerland): insights into the tidal-flat palaeoenvironment and dinosaur diversity, locomotion, and palaeoecology
by Daniel Marty
Marty, D. 2008: Sedimentology, taphonomy, and ichnology of Late Jurassic dinosaur tracks from the Jura carbonate platform (Chevenez—Combe Ronde tracksite, NW Switzerland): insights into the tidal-flat palaeoenvironment and dinosaur diversity, locomotion, and palaeoecology. PhD Thesis University of Fribourg, GeoFocus 21, 278 pp.
--> Award of the Science Faculty of the University of Fribourg for the best doctoral thesis of the year in the area of experimental sciences.
Dinosaur tracks are biogenic, sedimentary structures and not body fossils or biological objects in the common sense.... more
Dinosaur tracks are biogenic, sedimentary structures and not body fossils or biological objects in the common sense. They result from the complex interaction of the kinematics of the trackmaker, its foot anatomy, and the substrate properties, and from taphonomic processes acting prior to the incorporation of the tracks into the sedimentary record. The objective of this work is an interdisciplinary study of a large sample of dinosaur tracks and trackways linking sedimentology with vertebrate ichnology, palaeontology, and palaeoecology.
Excellent conditions are provided by the Late Jurassic (Kimmeridgian) Chevenez—Combe Ronde tracksite, which is one of several tracksites located on the future course of the Transjurane highway near Porrentruy (Canton Jura, NW Switzerland). Here, eight superimposed dinosaur track-bearing surfaces were systematically excavated level-by-level within a 0,65 m thick laminite interval, unearthing almost 1400 dinosaur tracks. The main track level, located at the base of the interval, is the most diverse ichnoassemblage composed of 14 trackways of tiny (Pes Length < 25 cm) and small (25 cm < PL < 50 cm) sauropods and 43 trackways of minute (PL < 10 cm), small (10 cm < PL < 20 cm), and medium-sized
(20 cm < PL < 30 cm) bipedal, tridactyl dinosaurs.
The main issues are: (1) identification of true tracks, undertracks, and overtracks, and their relationships with substrate properties, their link with the exposure index, and their utility in the reconstruction of the palaeoenvironment; (2) implications of the main track level ichnoassemblage for dinosaur behaviour, the terrestrial palaeoecosystem, and vertebrate ichnofacies; (3) relationships between variability in trackway patterns and configurations with locomotion speed, behaviour, and substrate properties as well as implications for locomotion capabilities; (4) Quantification and relevance of sauropod trackway gauge; and (5) interpretation of manus-dominated and pes-only sauropod trackways.
The approach is first actualistic by studying human footprints and processes acting during their formation and preservation on modern tidal-flats. In these highly structured environments, microbial mats are ubiquitous, strongly facies-specific, and occupy a key position during and after footprint formation. Undertracks readily form in biolaminated sediment, whilst underprints and deep tracks are common in unlaminated, water-saturated sediment. Most consolidated vertebrate tracks are affected by taphonomic processes, including renewed and/or repeated growth of microbial mats leading to the formation of modified true tracks, internal overtracks (track fills), and overtracks.
The sauropod tracks and the encasing laminite interval of the Combe Ronde site are then subject of detailed sedimentological and taphonomical analyses. This discloses the sediment properties at the time of track formation and reveals the processes modifying the tracks during subaerial exposure and integrating them into the sedimentary record. Track morphology, associated track features, and sedimentary features can be linked with the exposure index, identifying the palaeoenvironment as a supratidal flat not located in close proximity to a coastline. These flats were susceptible for track recording only during short periods after wetting due to a rainy period or due to occasional storms. Longer periods of subaerial exposure prior to burial are indicated by the presence of internal overtracks and/or overtracks, and rapid covering up is indicated by the lack of overtracks on top of tracks with large displacement rims. Cross-sections of sauropod tracks provide insight into the consolidation history of the substrate prior to track formation and into the walking dynamics of dinosaurs, confirming that sauropods put their hindfeet in a pronounced plantigrade way on the ground.
The level-by-level superimposition of the studied surfaces enables to identify true tracks, undertracks, and overtracks. The best-defined true tracks (anatomical morphotypes) of the main track level are then used for ichnotaxonomy and trackmaker identification, and the detailed analyses of trackway parameters, including trackway gauge, provide insight into the locomotion capabilities of dinosaurs.
The best-defined minute and small tridactyl tracks can be assigned to the ichnogenus Carmelopodus, extending it from the Middle Jurassic into the Late Jurassic. These tracks were likely left by a small theropod dinosaur similar in size to Compsognathus or Juravenator. The medium-sized tridactyl tracks of morphotype II exhibit some of the typical features of the ichnogenus Therangospodus (attributed to large and robust theropods) but also some of ornithopod ichnotaxa.
The sauropod trackways show a wide range of patterns and configurations but are all medium- to wide-gauge. Therefore, they are assigned tentatively to the ichnogenus Brontopodus attributed to derived “brachiosaurid” or “titanosaurid” dinosaurs. The variability of the trackways reflects the general locomotion capabilities of the trackmakers and is an expression of individual walking style and behaviour, which may be related to substrate properties. Trackway patterns (the degree of manus overprinting by the pes) and different trackway configurations including trackway gauge are not only related to locomotion speed, and they provide no evidence of a relationship with ontogeny.
The gauge of sauropod trackways can be quantified with the pes trackway ratio and the here defined [WAP/PL]-ratio (Width of the pes Angulation Pattern / Pes Length). Gauge is possibly related to the substrate and the behaviour of the trackmaker adapting to it, but this does not change the overall medium-gauge to wide-gauge appearance of the trackways. The manus-dominated and pes-only sauropod trackways of the Combe Ronde site are explained by trackmakers exerting more pressure on the manus than the pes, and by overprinting of the manus by the pes, respectively.
The alignment of trackways on the main track level shows no evidence of a nearby shoreline and of interactions between the different groups of dinosaurs. It indicates gregarious behaviour amongst tiny and small sauropods, and suggests that minute and small bipedal dinosaurs were frequent visitors on the supratidal flats.
The ichnoassemblage of the main track level is the first one found in the Jura Mountains displaying abundant minute and small tridactyl tracks. This is also typical for the other Ajoie ichnoassemblages, which further exhibit tracks of tiny to large (up to 1,1 m PL) sauropods, and tracks of medium-sized to large (up to 0,8 m PL) bipedal dinosaurs. Sauropod trackways include narrow-gauge and wide-gauge trackways indicating the presence of “basal” and derived sauropods. This suggests that dwarfed insular animals can be excluded as trackmakers of the tiny and small sauropod trackways of the Ajoie ichnoassemblages and the Combe Ronde tracksite and that the Jura carbonate platform was connected with the landmasses of the London-Brabant Massif and the Massif Central during periods of emersion. Dinosaurs used the Jura carbonate platform for the establishment of in situ, predominantly saurischian dinosaur populations, but also as a migration corridor between the massifs.
Because the Ajoie ichnoassemblages are dominated by small tridactyl tracks, they differ from other Jurassic tetrapod ichnofacies in carbonate settings, notably from the Brontopodus ichnofacies. In the case of those ichnoassemblages commonly attributed to the Brontopodus ichnofacies, the lack or rareness of small tridactyl tracks may indicate the absence of small trackmakers in those palaeoenvironments or unsuitable conditions for the formation and preservation of small tracks.
This study highlights the benefits of systematic and interdisciplinary analyses of dinosaur tracks, which disclose variations related to behaviour and to differences in substrate. This allows recognizing anatomical morphotypes and trackway configurations representative of typical trackmaker behaviour. The latter can then also be used in ichnotaxonomical classification. Similar approaches should be in the focus of future work and performed on the other tracksites and ichnoassemblages of the Ajoie. Together with the evidence from other tracksites of the Jura Mountains, this will contribute towards a better understanding of the terrestrial palaeoenvironments and palaeogeography, and of dinosaur palaeoecology and palaeobiogeography on the Jura carbonate platform.
Assinaturas icnológicas da sucessão sedimentar Rio Bonito no bloco central da jazida carbonífera de Iruí, Cachoeira do Sul (RS)
by Renata Netto
Authors: Rosana Gandini, Renata G. Netto, Henrique P. Kern, Ernesto L.C. Lavina
The subsurface deposits of the Rio Bonito sedimentary succession in the central block of the Iruí coal mine (Cachoeira... more The subsurface deposits of the Rio Bonito sedimentary succession in the central block of the Iruí coal mine (Cachoeira do Sul, Rio Grande do Sul State, S Brazil) is composed of sedimentary facies associations that represent deposition in dominantly marginal-marine and shallow-marine settings, the later in minor scale. Ichnofabrics of Chondrites, Chondrites-Helmintopsis-Planolites, Cylindrichnus-Thalassinoides, Helminthopsis, Macaronichnus, Ophiomorpha, Palaeophycus, Planolites, Thalassinoides, and Thalassinoides-Palaeophycus occur in the marginal marine settings, whereas the Thalassinoides-Palaeophycus-Helminthopsis ichnofabric is present in the shallow marine deposits. The marginal-marine ichnofabrics are characterized by the low bioturbation index, the reduced size of burrows, and the low ichnodiversity, whereas the marine ones show a moderate to high degree of bioturbation and low ichnodiversity. The ichnofabric pattern, its stratigraphic distribution, and its sedimentological relationships allow recognizing four ichnological signatures, three suggesting stress caused by changes in the salinity gradient, and one substrate-controlled. Ichnofabrics of Helmithopsis, Palapeophycus, and Planolites in lithofacies SiltArg suggest the dominance of oligohaline to freshwater conditions. Ichnofabrics of Thalassinoides-Palaeophycus and Cylindrichnus-Thalassinoides reflect the dominance of mesohaline conditions, each one representing, respectively, more quiet and stable environments (impoverished Cruziana Ichnofacies suite), and moderate to high energy settings (mixed Skolithos-Cruziana Ichnofacies suite). The Thalassinoides-Palaeophycus-Helminthopsis ichnofabric represents an arquetypical Cruziana Ichnofacies suite, indicating shallow marine settings. The reduced size of the burrows, however, suggests dominance of polyhaline rather than stenohaline conditions and its local distribution allow infer deposition in embayments, which mimic the environmental conditions found in the lower shorefce/offshore transition zones. The Thalassinoides ichnofabric is substrate-controlled, representing a Glossifungites Ichnofacies suite. It demarks two autogenic stratigraphic surfaces, and one allogenic stratigraphic surface interpreted as a sequence boundary. The integrated ichnological and sedimentological analysis in high resolution scale, allowed refining the existent paleoenvironmental and stratigraphic interpretations of the Rio Bonito sedimentary succession in the study area.
Analysis of variability in /Protichnites/ morphology and a standardized method of identification
Presented at the Ichnological Applications to Sedimentological and Sequence Stratigraphic Problems, SEPM Research Conference, May 20 - 26, 2007, Price, Utah, USA.
First paragraph:
Morphological characters of described specimens of the ichnogenus _Protichnites_ Owen, 1852, (a... more
First paragraph:
Morphological characters of described specimens of the ichnogenus _Protichnites_ Owen, 1852, (a probable arthropod trace fossil) in the literature were identified. For this study, _Protichnites_ was defined as a trackway possessing the following characteristics: paired imprints across the midline, medial structure (groove(s) or ridge(s)), and a countable (i.e., generally unchanging) number of tracks in each repeating trackset. This definition removes certain described specimens and ichnospecies of _Protichnites_ from that ichnogenus (and from this study), due mainly to a lack of ‘countable’ tracks per set, something that Owen (1852) considered an important aspect of these trackways when he named _P. septemnotatus_ (“seven-marked”), _P. octonotatus_ (“eight-marked”) and _P. multinotatus_ (“many-marked”). Specimens that possess this morphology but have not been identified as _Protichnites_ were not included in this study. Many specimens from the literature have been identified only to the level of ichnogenus.
A new occurrence of /Protichnites/ Owen, 1852, in the Late Cambrian Potsdam Sandstone of the St. Lawrence lowlands
Co-authored with J. Mark Erickson, published in The Open Paleontology Journal 3:1-13 (2010)
Late Cambrian arthropod trackways from the Potsdam Sandstone have been known since the 1850s. A site in Clinton... more Late Cambrian arthropod trackways from the Potsdam Sandstone have been known since the 1850s. A site in Clinton County, New York, USA, exposes _Protichnites_ in fine-grained, quartz-rich, rippled, micro-laminated Potsdam Sandstone. The study area includes evidence of microbial mat growth on the original surface where the trackways were produced. Ripple marks presumably underlie, and therefore were generated prior to, the microbial mat. Trackway preservation is variable over the outcrop and depositional setting indicates a high intertidal or a low supratidal environment with growth of benthic microbial mats. At least eleven distinguishable trackways of multi-legged, telson- bearing individuals show a range of widths. The trackways consist of repetitive sets of seven pairs of tracks converging in the direction of motion of the organism. A telson impression, either discontinuous or continuous, divides the trackways longitudinally and is nearly centered throughout the lengths of the trackways. The trackways are consistent in number of tracks per series, arrangement, and stride lengths with the ichnospecies holotype from the original description of _Protichnites septemnotatus_ Owen, 1852. Variable preservation probably resulted from varying thickness of the microbial mat and/or varying water depth or wind and wave action in an intertidal pool.