Pushing the limits of neutron tomography in palaeontology: Three-dimensional modelling of in situ resin within fossil plants

Mays, Chris; Bevitt, Joseph J.; Stilwell, Jeffrey D.

doi:10.26879/808

Cited by 26 publications

(24 citation statements)

References 31 publications

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“…This suggests that the early Late Cretaceous flora of the south polar region was dominated by members of this family. Macrofloral fossils typically have a coalified preservation style, and three-dimensional fossils show some distortion due to compaction (Mays et al, 2017a). Of the 21 macerated sediment samples examined from the Cenomanian section of the Tupuangi Formation, fossil resin specimens were recovered from all but one (Mays et al, 2017b); these are dispersed, small (typically b 1 cm in length), and generally tubular ( Fig.…”

Section: Mid-cretaceous Geology and Palaeontology Of The Chatham Islandsmentioning

confidence: 99%

The botanical provenance and taphonomy of Late Cretaceous Chatham amber, Chatham Islands, New Zealand

Mays

Coward

O’Dell

et al. 2019

Review of Palaeobotany and Palynology

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Fossil resin (amber) has been recently reported as common, but small, sedimentary components throughout the lower Upper Cretaceous (Cenomanian; 99-94 Ma) strata of the Tupuangi Formation, Chatham Islands, eastern Zealandia. From these deposits, resin has also been identified and obtained from well-preserved, coalified specimens of the conifer fossil Protodammara reimatamoriori Mays and Cantrill, 2018. Here, we employed attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) to both dispersed and in situ amber specimens. These resulted in very similar chemical signatures, indicating that these fossils are likely from the same or closely-related botanical sources. The FTIR data are typical of a conifer source within the 'cupressaceous resins' category of Tappert et al. (2011). Carbon-13 nuclear magnetic resonance spectroscopy (13 C NMR) facilitated the probable identification of these ambers as 'Class Ib' (sensu Anderson et al. 1992). Based on these spectral data sets, the likely botanical sources of the amber were either Araucariaceae or Cupressaceae; both of these conifer families were common and widespread in the Southern Hemisphere during the Cretaceous. However, the morphology and anatomy of P. reimatamoriori support an affinity to the latter family, thus indicating that the Cretaceous amber of the Chatham Islands was generally produced by members of the Cupressaceae. Comparing the FTIR data to the published spectra of modern resins, we also identify a band ratio which may aid in distinguishing between the FTIR spectra of Araucariaceae and Cupressaceae, and outline the limitations to this approach. A high concentration of ester bonds in Chatham amber specimens, which exceeds typical Cupressaceae resins, is probably caused by taphonomic alteration via thermal maturation. The source of thermal alteration was likely preburial wildfires, conditions for which P. reimatamoriori was adapted to as part of its life cycle. A comparison of ambers of the Chatham Islands with modern resins and amber from various localities in Australasia reveals that, taphonomic influences aside, Chatham amber has a unique signature, suggesting that members of the basal Cupressaceae (e.g., Protodammara) were not major contributors to other documented Australasian amber deposits. The closest analogy to Chatham amber deposits appears to be the Upper Cretaceous Raritan Formation, USA, which is characterised by its rich amber, charcoal and Cupressaceae fossil assemblages. This study further supports the hypotheses that the early Late Cretaceous south polar forests were dominated by Cupressaceae, and regularly disturbed by wildfires.

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Section: Mid-cretaceous Geology and Palaeontology Of The Chatham Islandsmentioning

confidence: 99%

The botanical provenance and taphonomy of Late Cretaceous Chatham amber, Chatham Islands, New Zealand

Mays

Coward

O’Dell

et al. 2019

Review of Palaeobotany and Palynology

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“…Each 11 h scan consisted of a total of 1200 equally-spaced angle shadow-radiographs obtained every 0.15 • as the sample was rotated 180 • about its vertical axis. To reduce anomalous noise, a total of three individual radiographs with an exposure length of 8 s were acquired at each angle [17] and individual radiographs were summed in post-acquisition processing in ImageJ v.1.51h. Tomographic reconstruction of the 16-bit Diversity 2020, 12, 46 3 of 12 raw data was performed using Octopus Reconstruction v.8.8 (Inside Matters NV, Gent, Belgium), yielding virtual slices perpendicular to the rotation axis.…”

Section: Methodsmentioning

confidence: 99%

First Complete Wing of a Stem Group Sphenisciform from the Paleocene of New Zealand Sheds Light on the Evolution of the Penguin Flipper

Mayr

Pietri

Love³

et al. 2020

Diversity

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We describe a partial skeleton of a stem group penguin from the Waipara Greensand in New Zealand, which is tentatively assigned to Muriwaimanu tuatahi. The fossil includes the first complete wing of a Paleocene penguin and informs on previously unknown features of the mandible and tibiotarsus of small-sized Sphenisciformes from the Waipara Greensand. The wing is distinguished by important features from that of all geologically younger Sphenisciformes and documents an early stage in the evolution of wing-propelled diving in penguins. In particular, the wing of the new fossil exhibits a well-developed alular phalanx and the distal phalanges are not flattened. Because the wing phalanges resemble those of volant birds, we consider it likely that the wing feathers remained differentiated into functional categories and were not short and scale-like as they are in extant penguins. Even though the flippers of geologically younger penguins may favor survival in extremely cold climates, they are likely to have been shaped by hydrodynamic demands. Possible selective drivers include a diminished importance of the hindlimbs in subaquatic propulsion, new foraging strategies (the caudal end of the mandible of the new fossil distinctly differs from that of extant penguins), or increased predation by marine mammals.

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“…Both dark (closed shutter) and beam profile (open shutter) images were obtained for calibration before initiating shadow-radiograph acquisition. To reduce anomalous noise, a total of three individual radiographs with an exposure length of 14s were acquired at each angle (Mays et al, 2017) for a total scan time of 13.5 h. The individual radiographs were summed in postacquisition processing using the "Grouped ZProjector" plugin in ImageJ v.1.51h in accordance with our previous measurements (Gee et al, 2019), and tomographic reconstruction of the 16-bit raw data accomplished using Octopus Reconstruction v.8.8.…”

Section: Methodsmentioning

confidence: 99%

A New Captorhinid From the Permian Cave System Near Richards Spur, Oklahoma, and the Taxic Diversity of Captorhinus at This Locality

2019

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Pushing the limits of neutron tomography in palaeontology: Three-dimensional modelling of in situ resin within fossil plants

Cited by 26 publications

References 31 publications

The botanical provenance and taphonomy of Late Cretaceous Chatham amber, Chatham Islands, New Zealand

The botanical provenance and taphonomy of Late Cretaceous Chatham amber, Chatham Islands, New Zealand

First Complete Wing of a Stem Group Sphenisciform from the Paleocene of New Zealand Sheds Light on the Evolution of the Penguin Flipper

A New Captorhinid From the Permian Cave System Near Richards Spur, Oklahoma, and the Taxic Diversity of Captorhinus at This Locality

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