Fast-running theropods tracks from the Early Cretaceous of La Rioja, Spain

Theropod behaviour and biodynamics are intriguing questions that paleontology has been trying to resolve for a long time. The lack of extant groups with similar bipedalism has made it hard to answer some of the questions on the matter, yet theoretical biomechanical models have shed some light on the question of how fast theropods could run and what kind of movement they showed. The study of dinosaur tracks can help answer some of these questions due to the very nature of tracks as a product of the interaction of these animals with the environment. Two trackways belonging to fast-running theropods from the Lower Cretaceous Enciso Group of Igea (La Rioja) are presented here and compared with other fast-running theropod trackways published to date. The Lower Cretaceous Iberian fossil record and some features present in these footprints and trackways suggest a basal tetanuran, probably a carcharodontosaurid or spinosaurid, as a plausible trackmaker. Speed analysis shows that these trackways, with speed ranges of 6.5–10.3 and 8.8–12.4 ms−1, testify to some of the top speeds ever calculated for theropod tracks, shedding light on the question of dinosaur biodynamics and how these animals moved.

Defining the Bemaraha megatracksite: an update on dinosaur ichnology in Madagascar

The Bemaraha Formation preserves a unique and abundant record of dinosaur footprints, the only occurrence of this type known from Madagascar. Theropod and sauropod tracks occur in Middle Jurassic strata and form an important record from this otherwise poorly documented time interval. Here we report on 18 new tracksites, raising the total number of known localities in the Bemaraha to 31. The majority of these sites occur at a same stratigraphic level that can be traced over an area of at least 30 km2, which makes it one of the most laterally extensive occurrences of dinosaur tracks on record in the southern hemisphere. Dinosaur tracks are restricted to a few bedding surfaces representing times of sea-level lowstand within a normally marine environment. Theropod tracks are by far more abundant than sauropod tracks and typically are oriented towards the palaeocoastline. This pattern is interpreted as evidence of a short-scale migration between feeding and resting grounds. The Bemaraha Formation thus allows a rare glimpse into dinosaur behaviour in a marginal marine environment of Jurassic age.

Fast-Running Theropods Tracks From the Early Cretaceous of La Rioja, Spain

Theropod behaviour and biodynamics are intriguing questions that paleontology has been trying to resolve for a long time. The lack of extant groups with similar bipedalism has made it hard to answer some of the questions on the matter, yet theoretical biomechanical models have shed some light on the question of how fast theropods could run and what kind of movement they showed. The study of dinosaur tracks can help answer some of these questions due to the very nature of tracks as a product of the interaction of these animals with the environment. Two trackways belonging to fast-running theropods from the Lower Cretaceous Enciso Group of Igea (La Rioja) are presented here and compared with other fast-running theropod trackways published to date. The Lower Cretaceous Iberian fossil record and some features present in these footprints and trackways suggest a basal tetanuran, probably a carcharodontosaurid or spinosaurid, as a plausible trackmaker. Speed analysis shows that these trackways, with speed ranges of 6.5−10.3 and 8.8−12.4 ms-1, testify to some of the top speeds ever calculated for theropod tracks, shedding light on the question of dinosaur biodynamics and how these animals moved.

A reevaluation of the Late Jurassic dinosaur tracksite Barkhausen (Wiehengebirge, Northern Germany)

A restudy of the Barkhausen dinosaur tracksite shows that the track-bearing surface reveals considerably more detail than previously indicated, and a new map is presented, showing the trackways of nine sauropods, traveling north, possibly as a group. These are among the smallest sauropod tracks recorded in Europe. There is also evidence of two large theropods crossing the area, one moving to the south and the other to the west. Evidence of at least three other sauropods is registered in the form of isolated manus traces that represent larger individuals. Previous interpretations inferred that sauropod trackways trended south, and therefore suggested a predator chasing its prey as in the purported but controversial attack scenario claimed for the famous Paluxy River site in Texas. Based on the present study, this scenario is no longer tenable for the Barkhausen tracksite. The description of Elephantopoides barkhausensis (Kaever and Lapparent, 1974) shows that it represents a moderately wide gauge, but small manus sauropod and can be assigned under the ichnofamily label Parabrontopodidae. E. barkhausensis as originally defined was a nomen dubium, but it has since been re-described semi-formally, without renaming, we emend the description and assigned them to the ichnotaxon Parabrontopodus barkhausensis comb. nov. These tracks could have been produced by the small sauropod dinosaur taxon Europasaurus. The problematic ichnotaxon Megalosauropus teutonicus (Kaever and Lapparent, 1974), which represents a large three-toed theropod, is assigned to the recently described ichnogenus Jurabrontes from the Late Kimmeridgian of the Swiss Jura mountains as Jurabrontes teutonicus comb. nov. Furthermore, we attribute the theropod tracks from the time equivalent Langenberg quarry to the same ichnotaxon.

The new ichnotaxon Eubrontes nobitai ichnosp. nov. and other saurischian tracks from the Lower Cretaceous of Sichuan Province and a review of Chinese Eubrontes-type tracks

The Jiaguan Formation and the underlying Feitianshan Formation (Lower Cretaceous) in Sichuan Province yield multiple saurischian (theropod–sauropod) dominated ichnofaunas. To date, a moderate diversity of six theropod ichnogenera has been reported, but none of these have been identified at the ichnospecies level. Thus, many morphotypes have common “generic” labels such as Grallator, Eubrontes, cf. Eubrontes or even “Eubrontes-Megalosauripus” morphotype. These morphotypes are generally more typical of the Jurassic, whereas other more distinctive theropod tracks (Minisauripus and Velociraptorichnus) are restricted to the Cretaceous. The new ichnospecies Eubrontes nobitai ichnosp nov. is distinguished from Jurassic morphotypes based on a very well-preserved trackway and represents the first-named Eubrontes ichnospecies from the Cretaceous of Asia.

Theropod tracks from the Jurassic–Cretaceous boundary, Tuchengzi Formation, Chengde, China: Review and new observations

Previously known theropod dinosaur footprints preserved as natural casts in the Tuchengzi Formation, on a rock wall beside the railway in Nanshuangmiao Village, Shangbancheng Town, Chengde City, were originally assigned to ichnogenus Anchisauripus and tentatively attributed to oviraptosaurs. The assemblage was restudied in more detail by examining the entire assemblage of 55 tracks associated with two horizons. The size range of the 27 measured tracks suggests a more diverse grallatorid–eubrontid assemblage and potentially greater diversity of theropod trackmakers. The label Anchisauripus, which has fallen into disuse in some recent literature, implies trackmakers of medium shape and size in the grallatorid–eubrontid morphological spectrum. However, given the presence of other theropod ichnotaxa in the Jurassic to Early Cretaceous strata of the Tuchengzi Formation and time equivalent units we suggest that explicit reference to the Grallator-Anchisauripus-Eubrontes (GAE) plexus, or simply the term Grallator-Eubrontes plexus be confined to Lower Jurassic assemblages as originally defined and intended. Further study centered on the 16 known Tuchengzi assemblages and older theropod ichnfaunas is necessary to confirm or refute the degree to which grallatorid–eubrontid assemblages from these different epochs are similar or convergent. Even if the tracks are morphologically very similar inferences regarding trackmaker identity are problematic because the same theropodan trackmaker species, genera or even families were not present in both epochs.

First report of deinonychosaurian trackway from the Cretaceous of Guizhou, China

The southern edge of Sichuan Basin has a long-standing folklore about the Tian Ji Stone, which actually tells of the theropod tracks. Here we describe a new Tian Ji track site named Xinglongwan in Chishui, Guizhou Province, China. Two kilometers away from the old site recorded in 2011, the later with cf. Irenesauripus isp. are morphologically different from the Xinglongwan theropod tracks. The tridactyl tracks from Xinglongwan site have been assigned to the cf. Eubrontes. Didactyl tracks in the Xinglongwan site, which are the first discovery of deinonychosaurian tracks in Guizhou Province, are assigned to the Velociraptorichnus. Both tracks were recorded in the report about ichnofauna in Jiaguan Formation, representing the diversity of theropod tracks in Sichuan Basin. The authors also briefly discuss the preservation mode and potential external-morphological changes of cf. Eubrontes and Velociraptorichnus from Xinglongwan site.

STEGOSAUR TRACK ASSEMBLAGE FROM XINJIANG, CHINA, FEATURING THE SMALLEST KNOWN STEGOSAUR RECORD

ABSTRACT Tracks attributable to small ornithischian dinosaurs (thyreophorans and cerapodans) are generally rare in comparison with those representing large individuals. Here we report a presumed stegosaur track (ichnogenus Deltapodus) only 5.7 cm long originating from the Lower Cretaceous Tugulu Group of Xinjiang Province, China, co-occurring with the tracks of larger individuals. This track is only 15% as long as the type of Deltapodus curriei from the same locality. This is the smallest convincing example of a Deltapodus currently known. Reports of purported diminutive stegosaur tracks from the Jurassic of North America have been refuted. A review of well-known ornithischian track ichnogenera reveals that small tracks, less than 11.0–12.0 cm are rare, with only one previous report of a Deltapodus only 8.0 cm long. Most other reported tracks of these ichnogenera represent large individuals with footprint lengths mostly in the range of 30–50 cm. The scarcity of small ornithischian tracks contrasts with the relative abundance of small theropod tracks. The reasons for this paucity of small ornithischian tracks may be due to paleobiological (ontogenetic or paleoecological) or non-paleobiological (preservational) factors.