The distribution of theropod-dominated ichnofaunas in the Moab Megatracksite area, Utah: implications for Late Jurassic palaeobiology along an arid coast

Historical Biology, Journal Year: 2021, Volume and Issue: 34(9), P. 1717 - 1751

Published: Oct. 4, 2021

The Late Jurassic, 'single surface' Moab Megatracksite between Green River, Utah and the Colorado-Utah State line is associated with sharp, colour-enhanced, inter-formational contact white, reworked dune sandstones from aeolian Member of Curtis Formation red, sabkha facies siltstones upper tongue Summerville Formation. Previous studies described theropod (Megalosauripus Therangospodus) dominated assemblages ~25 sites in megatracksite core area around Arches National Park, briefly interpreted transgressive mechanisms Sundance sea which helped create preserve megatracksite.Since 1990s ~20 newly studied tracksites reveal a cumulative total ~4,300 tracks three are now designated as, federally managed, interpretative tourist destinations. Similar track assemblages, collectively constituting Megalosauripus-Therangospodus ichnocoenoses have also been found at lower stratigraphical levels J-3 Unconformity zones. These new discoveries relate to stratigraphic short-term changes Sea level affecting coastal (Slick Rock members) across low gradient, inter- sub-tidal sand flats, sabkha-like deposits under arid conditions. multiple (>50) ichnofaunas integral palaeobiological understanding an no body fossils known.

Language: Английский

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Size-mediated competition and community structure in a Late Cretaceous herbivorous dinosaur assemblage

Historical Biology, Journal Year: 2021, Volume and Issue: 34(11), P. 2230 - 2240

Published: Dec. 8, 2021

It has been argued that, throughout the Mesozoic, immature growth forms of megaherbivorous dinosaurs competitively excluded small herbivorous dinosaur species, leading to left-skewed species richness-body mass distributions their fossil assemblages. By corollary, where large and herbivores coexisted over a geologically significant period time, they must have exhibited niche partitioning. We use multivariate ecomorphological analysis Late Cretaceous ornithischian assemblage North America examine this prediction. Our results indicate good separation most, but not all, at body size, although more work is required demonstrate that these patterns were adaptive. Calculation browse profiles using corrected abundance data bracketed estimates energy requirements suggests megaherbivores – most particularly hadrosaurids outstripped coexisting in control resource base.

Language: Английский

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Large, unwebbed bird and bird‐like footprints from the Mesozoic and Cenozoic: a review of ichnotaxonomy and trackmaker affinity

Lethaia, Journal Year: 2021, Volume and Issue: 54(5), P. 969 - 987

Published: Dec. 1, 2021

The Mesozoic and Cenozoic track record of large birds (avian theropods) with footprint lengths (FL) > 10.0 cm is quite limited, whereas small tracks (FL < cm) are abundant from the Early Cretaceous onwards. This versus threshold value consistent extant among which only ˜10% large, so scaled appropriately to Class Aves. proportion pachydactylous (thick-toed) or robust non-avian theropod ichnotaxa reported considerably exceeds few leptodactylous (thin-toed) gracile forms such as Archaeornithipus Magnoavipes, named, albeit controversially, suggest avian affinity. different, limited a Eocene-Oligocene (Palaeogene) ichnogenera (Ornithoformipes Rivavipes), rare unnamed Neogene Holocene dinornithiform tracks. Thus, flightless species less well represented by than body fossils. suggests probable preservational bias in favour waterbird shorebird-like shoreline facies. However, attributable cranes, herons related trackmakers extensive, mostly confined formally named representatives clades capable flight. These distribution patterns apparently reflect dominance theropods early Palaeogene, contrast rise ongoing diversification smaller Aequornithes Neogene. space time likely changing selection pressures today's modern avifauna evolved.

Language: Английский

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Small, immature pterosaurs from the Cretaceous of Africa: implications for taphonomic bias and palaeocommunity structure in flying reptiles

Cretaceous Research, Journal Year: 2021, Volume and Issue: 130, P. 105061 - 105061

Published: Oct. 19, 2021

Language: Английский

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Comment on “The influence of juvenile dinosaurs on community structure and diversity”

Science, Journal Year: 2022, Volume and Issue: 375(6578)

Published: Jan. 20, 2022

Schroeder et al. (Reports, 26 February 2021, p. 941) reported a size gap among predatory dinosaur species. We argue that the supporting dataset is skewed toward Late Cretaceous North America and was likely absent during other intervals in most geographic regions. urge broader consideration of this hypothesis, with quantitative evaluation preservational biases.

Language: Английский

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