An enigmatic plant-eating theropod from the Late Jurassic period of Chile

Novas, Fernando E.; Salgado, Leonardo; Suárez, Manuel; Agnolín, Federico; Ezcurra, Martín D.; Chimento, Nicolás Roberto; Cruz, Rita De La; Isasi, Marcelo P.; Vargas, Alexander O.; Rubilar-Rogers, David

doi:10.1038/nature14307

Cited by 71 publications

(66 citation statements)

References 20 publications

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“…; Novas et al . ). In fact, 1 kg is large for extant bird species, which have a modal body mass around 100 g (Brown ).…”

Section: Discussionmentioning

confidence: 97%

“…), the ceratopsian Graciliceratops (Maryanska & Osmólska ), mononychine theropods (which have small body sizes but occur after the Aptian and so could not be analysed in our study) and also the early possible tetanuran Chilesaurus (~1 kg; immature individual; Novas et al . ) (Table ). Chilesaurus was not included in our analyses because adult mass estimates are not available.…”

Section: Discussionmentioning

confidence: 99%

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Cope's rule and the adaptive landscape of dinosaur body size evolution

et al. 2017

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The largest known dinosaurs weighed at least 20 million times as much as the smallest, indicating exceptional phenotypic divergence. Previous studies have focused on extreme giant sizes, tests of Cope's rule, and miniaturization on the line leading to birds. We use non-uniform macroevolutionary models based on Ornstein-Uhlenbeck and trend processes to unify these observations, asking: what patterns of evolutionary rates, directionality and constraint explain the diversification of dinosaur body mass? We find that dinosaur evolution is constrained by attraction to discrete body size optima that undergo rare, but abrupt, evolutionary shifts. This model explains both the rarity of multilineage directional trends, and the occurrence of abrupt directional excursions during the origins of groups such as tiny pygostylian birds and giant sauropods. Most expansion of trait space results from rare, constraint-breaking innovations in just a small number of lineages. These lineages shifted rapidly into novel regions of trait space, occasionally to small sizes, but most often to large or giant sizes. As with Cenozoic mammals, intermediate body sizes were typically attained only transiently by lineages on a trajectory from small to large size. This demonstrates that bimodality in the macroevolutionary adaptive landscape for land vertebrates has existed for more than 200 million years.

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“…; Novas et al . ). In fact, 1 kg is large for extant bird species, which have a modal body mass around 100 g (Brown ).…”

Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Cope's rule and the adaptive landscape of dinosaur body size evolution

et al. 2017

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“…Barrett, 2014, and references therein), except for a tentative coupling between the decline of cycadophytes and stegosaurs during the earliest Cretaceous (Butler et al, 2009a,b). The only known herbivorous tetanuran theropod lineage in the Jurassic has no known Cretaceous representative (Novas et al, 2015). It has been suggested that medium-sized theropods underwent a substantial decline across the J/K boundary, and were replaced by larger-bodied carcharodontosaurids and spinosaurids (Novas et al, 2013;Tortosa et al, 2014).…”

Section: (3) Biotic Interactions and Evidence For A Faunal Turnover (mentioning

confidence: 99%

Biotic and environmental dynamics through theLateJurassic–EarlyCretaceous transition: evidence for protracted faunal and ecological turnover

et al. 2016

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The Late Jurassic to Early Cretaceous interval represents a time of environmental upheaval and cataclysmic events, combined with disruptions to terrestrial and marine ecosystems. Historically, the Jurassic/Cretaceous (J/K) boundary was classified as one of eight mass extinctions. However, more recent research has largely overturned this view, revealing a much more complex pattern of biotic and abiotic dynamics than has previously been appreciated. Here, we present a synthesis of our current knowledge of Late Jurassic-Early Cretaceous events, focusing particularly on events closest to the J/K boundary. We find evidence for a combination of short-term catastrophic events, large-scale tectonic processes and environmental perturbations, and major clade interactions that led to a seemingly dramatic faunal and ecological turnover in both the marine and terrestrial realms. This is coupled with a great reduction in global biodiversity which might in part be explained by poor sampling. Very few groups appear to have been entirely resilient to this J/K boundary 'event', which hints at a 'cascade model' of ecosystem changes driving faunal dynamics. Within terrestrial ecosystems, larger, more-specialised organisms, such as saurischian dinosaurs, appear to have suffered the most. Medium-sized tetanuran theropods declined, and were replaced by larger-bodied groups, and basal eusauropods were replaced by neosauropod faunas. The ascent of paravian theropods is emphasised by escalated competition with contemporary pterosaur groups, culminating in the explosive radiation of birds, although the timing of this is obfuscated by biases in sampling. Smaller, more ecologically diverse terrestrial non-archosaurs, such as lissamphibians and mammaliaforms, were comparatively resilient to extinctions, instead documenting the origination of many extant groups around the J/K boundary. In the marine realm, extinctions were focused on low-latitude, shallow marine shelf-dwelling faunas, corresponding to a significant eustatic sea-level fall in the latest Jurassic. More mobile and ecologically plastic marine groups, such as ichthyosaurs, survived the boundary relatively unscathed. High rates of extinction and turnover in other macropredaceous marine groups, including plesiosaurs, are accompanied by the origin of most major lineages of extant sharks. Groups which occupied both marine and terrestrial ecosystems, including crocodylomorphs, document a selective extinction in shallow marine forms, whereas turtles appear to have diversified. These patterns suggest that different extinction selectivity and ecological processes were operating between marine and terrestrial ecosystems, which were ultimately important in determining the fates of many key groups, as well as the origins of many major extant lineages. We identify a series of potential abiotic candidates for driving these patterns, including multiple bolide impacts, several episodes of flood basalt eruptions, dramatic climate change, and major disruptions to oceanic systems. The J/K t...

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“…They were predominantly carnivorous, but some derived lineages evolved omnivorous and herbivorous diets (Barrett , ; Zanno & Makovicky ; Novas et al . ; Lautenschlager ). Non‐avian theropod fossils have been found on all continents and in all environments, occupying an array of ecological niches (Henderson ; Amiot et al .…”

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confidence: 99%

Skeletal completeness of the non‐avian theropod dinosaur fossil record

Cashmore

Butler

2019

Palaeontology

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Non‐avian theropods were a highly successful clade of bipedal, predominantly carnivorous, dinosaurs. Their diversity and macroevolutionary patterns have been the subject of many studies. Changes in fossil specimen completeness through time and space can bias our understanding of macroevolution. Here, we quantify the completeness of 455 non‐avian theropod species using the skeletal completeness metric (SCM), which calculates the proportion of a complete skeleton preserved for a specimen. Temporal patterns of theropod skeletal completeness show peaks in the Carnian, Oxfordian–Kimmeridgian and Barremian–Aptian, and lows in the Berriasian and Hauterivian. Lagerstätten primarily drive the peaks in completeness and observed taxonomic diversity in the Oxfordian–Kimmeridgian and the Barremian–Aptian. Theropods have a significantly lower distribution of completeness scores than contemporary sauropodomorph dinosaurs but change in completeness through time for the two groups shows a significant correlation when conservation Lagerstätten are excluded, possibly indicating that both records are primarily driven by geology and sampling availability. Our results reveal relatively weak temporal sampling biases acting on the theropod record but relatively strong spatial and environmental biases. Asia has a significantly more complete record than any other continent, the mid northern latitudes have the highest abundance of finds, and most complete theropod skeletons come from lacustrine and aeolian environments. We suggest that these patterns result from historical research focus, modern climate dynamics, and depositional transportation energy plus association with conservation Lagerstätten, respectively. Furthermore, we find possible ecological biases acting on different theropod subgroups, but body size does not influence theropod completeness on a global scale.

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An enigmatic plant-eating theropod from the Late Jurassic period of Chile

Cited by 71 publications

References 20 publications

Cope's rule and the adaptive landscape of dinosaur body size evolution

Cope's rule and the adaptive landscape of dinosaur body size evolution

Biotic and environmental dynamics through theLateJurassic–EarlyCretaceous transition: evidence for protracted faunal and ecological turnover

Skeletal completeness of the non‐avian theropod dinosaur fossil record

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