A new multi-faceted framework for deciphering diplodocid ontogeny

Woodruff, D. Cary; Fowler, Denver W.; Horner, John R.

doi:10.26879/674

Cited by 19 publications

(38 citation statements)

References 122 publications

(238 reference statements)

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“…Using this adult cranial:body length ratio predicts a maximum body length of 9 m for CMC VP14128 and 10.9 m for CM 11255, a difference that would be even greater with a more realistic allometric skull-body length ratio; yet even this isometric trend indicates a minimum difference of nearly 2 m in body length, expressed in ~5 cm of cranial length-difference. While we await more specimens to fill in these crucial ontogenetic intervals, assuming size covaries with age at this locality (see Discussion), we hypothesize that CMC VP14128 was within the recorded MDQ ages of two – six years of age 5 and had a body length well under the isometrically calculated 9 m (Fig. 1 ).…”

Section: Resultsmentioning

confidence: 87%

“…M-166). The MDQ is a monodominant bone bed containing the remains of at least sixteen small diplodocines 6 , 7 (recorded femur lengths between 59.5 cm–120 cm 5 , 8 ). While five partial braincases have previously been collected from the MDQ, CMC VP14128 is the only complete skull found at the site.…”

Section: Methodsmentioning

confidence: 99%

“…Furthermore, recent analyses indicate that diplodocids, and potentially all sauropods, underwent allometric growth, and consequently radical ontogenetic trajectories 3 , 5 , 13 , 14 . The documentation of specimens that fill voids in our understanding of sauropod ontogeny is critical.…”

Section: Methodsmentioning

confidence: 99%

“…An adult Diplodocus might attain a body length in excess of 30 m 1 , but its skull was well under 1 m 2 . To date only three of these skulls are hypothesized to be from immature animals 3 – 5 , thus biasing our understanding of this taxon’s ontogeny, ecology, and evolution towards adult specimens. While few, these immature skulls reveal insights into cranial allometry through ontogeny and suggest that Diplodocus and its Diplodocidae kin underwent radical ontogenetic change.…”

Section: Introductionmentioning

confidence: 99%

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The Smallest Diplodocid Skull Reveals Cranial Ontogeny and Growth-Related Dietary Changes in the Largest Dinosaurs

Woodruff

Carr

Storrs

et al. 2018

Sci Rep

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Sauropod dinosaurs were the largest terrestrial vertebrates; yet despite a robust global fossil record, the paucity of cranial remains complicates attempts to understand their paleobiology. An assemblage of small diplodocid sauropods from the Upper Jurassic Morrison Formation of Montana, USA, has produced the smallest diplodocid skull yet discovered. The ~24 cm long skull is referred to cf. Diplodocus based on the presence of several cranial and vertebral characters. This specimen enhances known features of early diplodocid ontogeny including a short snout with narrow-crowned teeth limited to the anterior portion of the jaws and more spatulate teeth posteriorly. The combination of size plus basal and derived character expression seen here further emphasizes caution when naming new taxa displaying the same, as these may be indicative of immaturity. This young diplodocid reveals that cranial modifications occurred throughout growth, providing evidence for ontogenetic dietary partitioning and recapitulation of ancestral morphologies.

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Section: Resultsmentioning

confidence: 87%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Smallest Diplodocid Skull Reveals Cranial Ontogeny and Growth-Related Dietary Changes in the Largest Dinosaurs

Woodruff

Carr

Storrs

et al. 2018

Sci Rep

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“…Juvenile specimens can create problems for phylogenetic analyses, because some of the 188 traits change throughout ontogeny, such that only adult individuals display the derived state 189 necessary for a correct identification (Woodruff et al 2017). Indeed, in some analyses, juveniles 190…”

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confidence: 99%

The challenges and potential utility of phenotypic specimen-level phylogeny based on maximum parsimony

Tschopp

Upchurch

2018

Earth and Environmental Science Transactions of the Royal Socie

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16Specimen-level phylogenetic approaches are widely used in molecular biology for 17 taxonomic and systematic purposes. However, they have been largely ignored in analyses based on 18 morphological traits, where phylogeneticists mostly resort to species-level analyses. Recently, a 19 number of specimen-level studies have been published in vertebrate paleontology. These studies 20indicate that specimen-level phylogeny may be a very useful tool for systematic reassessments at 21 low taxonomic levels. Herein, we review the challenges when working with individual organisms as 22 operational taxonomic units in a paleontological context, and propose guidelines of how best to 23 perform a specimen-level phylogenetic analysis using the maximum parsimony criterion. Given that 24no single methodology appears to be perfectly suited to resolve relationships among individuals, 25and that different taxa probably require different approaches to assess their systematics, we 26advocate the use of a number of methodologies. In particular, we recommend the inclusion of as 27 many specimens and characters as feasible, and analysis of relationships using an extended implied 28 weighting approach with different downweighting functions. Resulting polytomies should be 29 explored using a posteriori pruning of unstable specimens, and conflicting tree topologies between 30 different iterations of the analysis should be evaluated by a combination of support values such as 31 jackknifing and symmetric resampling. Species delimitation should be consistent among the 32 ingroup and based on a reproducible approach. Although time-consuming and methodologically 33 challenging, specimen-level phylogenetic analysis is a highly useful tool to assess intraspecific 34 variability and provide the basis for more informed and accurate creation of species-level 35 operational taxonomic units in large-scale systematic studies. It also has the potential to inform us 36 about past speciation processes, morphological trait evolution, and their potential intrinsic and 37 extrinsic drivers in preeminent detail. 38Keywords. character weighting, cladistics, parsimony, species delimitation, vertebrate morphology 39 40 3 41 Specimen-level phylogenetic analysis is becoming increasingly popular in vertebrate 42 paleontology, in particular (but not only) in dinosaur systematics (This kind of phylogenetic analysis includes single specimens instead of species or genera as 46 operational taxonomic units (OTUs), and thus ignores earlier species-and/or genus-level 47 2004; Boyd et al. 2009; Scannella et al. 2014; Longrich 2015; Mounier & Caparros 2015; Tschopp 59 et al. 2015; Campbell et al. 2016). 60 Longrich (2015) and Tschopp et al. (2015) specifically highlighted the ability of specimen-61 level phylogenetic analyses to act as a test for homology of particular morphological features, and 62 thus to assess a trait's phylogenetic informativeness versus its status as intraspecific variation. This 63 issue is particularly important in vertebrate paleontology, where many s...

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The first occurrence of an avian-style respiratory infection in a non-avian dinosaur

Woodruff

Wolff

Wedel

et al. 2022

Sci Rep

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Other than repaired fractures, osteoarthritis, and periosteal reaction, the vertebrate fossil record has limited evidence of non-osseous diseases. This difficulty in paleontological diagnoses stems from (1) the inability to conduct medical testing, (2) soft-tissue pathologic structures are less likely to be preserved, and (3) many osseous lesions are not diagnostically specific. However, here reported for the first time is an avian-style respiratory disorder in a non-avian dinosaur. This sauropod presents irregular bony pathologic structures stemming from the pneumatic features in the cervical vertebrae. As sauropods show well-understood osteological correlates indicating that respiratory tissues were incorporated into the post-cranial skeleton, and thus likely had an ‘avian-style’ form of respiration, it is most parsimonious to identify these pathologic structures as stemming from a respiratory infection. Although several extant avian infections produce comparable symptoms, the most parsimonious is airsacculitis with associated osteomyelitis. From actinobacterial to fungal in origin, airsacculitis is an extremely prevalent respiratory disorder in birds today. While we cannot pinpoint the specific infectious agent that caused the airsacculitis, this diagnosis establishes the first fossil record of this disease. Additionally, it allows us increased insight into the medical disorders of dinosaurs from a phylogenetic perspective and understanding what maladies plagued the “fearfully great lizards”.

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A new multi-faceted framework for deciphering diplodocid ontogeny

Cited by 19 publications

References 122 publications

The Smallest Diplodocid Skull Reveals Cranial Ontogeny and Growth-Related Dietary Changes in the Largest Dinosaurs

The Smallest Diplodocid Skull Reveals Cranial Ontogeny and Growth-Related Dietary Changes in the Largest Dinosaurs

The challenges and potential utility of phenotypic specimen-level phylogeny based on maximum parsimony

The first occurrence of an avian-style respiratory infection in a non-avian dinosaur

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