Chris Mays

Polar wildfires and conifer serotiny during the Cretaceous global hothouse

Several highly effective fire-adaptive traits first evolved among modern plants duringthe mid-Cretaceous, in response to the widespread wildfires promoted by anomalously highatmospheric oxygen (O2) ...

Judging an acritarch by its cover: the taxonomic implications of Introvertocystis rangiaotea gen. et sp. nov. from the Late Cretaceous (Cenomanian–Turonian) of the Chatham Islands, New Zealand

Described here is a small acritarch with a fine reticulation on the internal surface of the cyst wall which provides a new criterion for future acritarch taxonomy. Sixty-six specimens of Introvertocystis rangiaotea gen. et sp. nov. have been identified from sediments of Ngaterian to Arowhanan age (Cenomanian to early Turonian; c. 99–92 Ma) within the Tupuangi Formation, Chatham Islands, New Zealand. The diagnostic feature of this fossil cyst is internal reticulation. This requires the emendment of the genus Palaeostomocystis. Some specimens may show waist constriction; this constriction is more common in larger specimens where it is suggestive of a paracingulum. However, the absence of a definite paracingulum, parasulcus or definable archeopyle precludes its assignment within the dinoflagellates. The wall structure is unusual in that the sculptural ornamentation is present on the internal surface, a feature that distinguishes it from all known acritarch genera.

Neutron tomography of Austrosequoia novae-zeelandiae comb. nov. (Late Cretaceous, Chatham Islands, New Zealand): implications for Sequoioideae phylogeny and biogeography

The Tupuangi Flora of the Chatham Islands, New Zealand, reveals a south polar forest ecosystem, and important biogeographical links between eastern and western Gondwana. We employed neutron tomography (NT) to image fossil Cupressaceae seed cones from the Upper Cretaceous (Cenomanian) strata of the Tupuangi Formation. This technique facilitated the non-destructive ‘virtual extraction’ of three-dimensional, coalified specimens, whilst they were still embedded within a large volume of supporting silicate sedimentary rock. This study is the first reported application of NT in palaeobotanical taxonomy, and the combination of virtual and manual extraction techniques enabled a more complete treatment than would otherwise be possible if taxonomic data were limited to only one of these approaches. The seed cones were identified as Austrosequoia novae-zeelandiae (Ettingshausen) Mays & Cantrill comb. nov. In this case, NT data supplemented the compression fossil data by providing details such as the three-dimensional measurements of the gross morphology, and accurate estimations of bract-scale complex number. Furthermore, this technique appears to show promise in differentiating between organic compounds within an individual specimen. However, anatomical details and fine-scale morphology were indiscernible due to present limitations in spatial resolution. Austrosequoia novae-zeelandiae is interpreted as a stem group of Sequoioideae; it shares synapomorphic seed cone characters with extant sequoioids (e.g. Sequoia and Sequoiadendron), and plesiomorphic stomatal structures and leaf morphology. Abundant epiphyllous fungi (Plochmopeltinites sp.; Microthyriaceae) were also identified on the leaf cuticles of A. novae-zeelandiae. The high abundance of Austrosequoia in the Tupuangi Flora supports a cupressaceous floral province at south polar latitudes during the early Late Cretaceous. Furthermore, this stem group of Sequoioideae in eastern Gondwana during the early Late Cretaceous suggests an alternative, south-to-north dispersal route of sequoioids before the final continental separation of eastern and western Gondwana.

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

Computed tomography is an increasingly popular technique for the non-destructivestudy of fossils. Whilst the science of X-ray computed tomography (CT) has greatlymatured since its first fossil appl ...

The range of bioinclusions and pseudoinclusions preserved in a new Turonian (~90 ma) amber occurrence from Southern Australia.

A new Turonian amber occurrence, representing the oldest in situ amber locality in Australia and the southern-most locality in Gondwana, has recently been discovered in the Otway Basin of Victoria. The amber was collected from petroleum cores and many pieces contain a range of inclusions that can provide information on the depositional history of the resin. To date, one species of fern spore (Cyathidites minor) and one species of lycophyte spore (Kraeuselisporites sp?) have been conclusively identified in the amber, along with filamentous microorganisms and degraded plant matter. Several samples are also rife with pseudoinclusions as reported recently in other ambers. The abundance of preserved particulate debris and wind dispersed spores suggest that the Otway amber formed subaerially. Furthermore, based on the range of bioinclusions and forms of pseudoinclusions preserved within a single piece of amber, the locus of hardening for individual samples is variably interpreted as occurring in the tree tops, on the tree trunk or on the ground surface. Notably, specific inclusion assemblages are associated with certain colours of amber. By extension, and in accordance with recent studies, amber colour may be indicative of depositional environment. Variation in the environment of solidification may, therefore, be sufficient to account for the broad range of morphological characteristics preserved in a single amber deposit.

Palaeoenvironmental reconstruction of Livingston Island, Antarctic Peninsula, in the Early Cretaceous: interpretations from the Walker Bay erratics

Chen, K., Stilwell, J.D. & Mays, C., 12.3.2015. Palaeoenvironmental reconstruction of Livingston Island, Antarctic Peninsula in the Early Cretaceous: interpretations from the Walker Bay erratics. Alcheringa 39, 000–000. ISSN 0311-551 Fossiliferous, volcaniclastic sandstone erratics, containing abundant plant fragments, palynomorphs and a possible insect wing, were extracted from the previously unstudied Walker Bay moraine, Livingston Island (ca 62°36ʹS, 60°42ʹW). These samples provide new insights into high southern latitude ecosystems of the South Shetland Islands region during the Early Cretaceous greenhouse interval. The palynofloral assemblage, in particular the co-occurrence of Ischyosporites punctatus, Concavissimisporites penolaensis and Reticulatisporites pudens, suggests that deposition could have occurred between the early Aptian and mid-Albian (ca 125–109 Ma), but was most likely early to mid-Albian (ca 112–109 Ma). The high relative abundance of the pteridophyte taxon, Cyathidites and associated fungal disaster taxa, together with significant quantities of volcaniclastic material, indicates a volcanically perturbed post-eruption riparian environment. Petrologic evidence suggests that the volcanic sediments were deposited rapidly in the above-mentioned fluvial setting. Comparisons to geological studies conducted on Livingston Island reveal an affinity of the Walker Bay erratics to the Byers Group; the unique palynofloral assemblage and petrological features of the erratics suggesting that the volcanogenic lithic sandstone facies may represent a previously undescribed unit of the upper Cerro Negro Formation. Kevin Chen [kevin.chen@monash.edu], Jeffrey D. Stilwell* [jeffrey.stilwell@monash.edu] & Chris Mays [chris.mays@monash.edu], School of Earth, Atmosphere and Environment, Faculty of Science, Monash University, Vic 3800, Australia. *Also affiliated with Australian Museum, 6 College Street, Sydney, NSW 2000, Australia.

Protodammara reimatamoriori, a new species of conifer (Cupressaceae) from the Upper Cretaceous Tupuangi Formation, Chatham Islands, Zealandia

Mays, C. & Cantrill, D.J., 4 January 2018. Protodammara reimatamoriori, a new species of conifer (Cupressaceae) from the Upper Cretaceous Tupuangi Formation, Chatham Islands, Zealandia. Alcheringa 43,, 114–126. ISSN 0311-5518. Isolated conifer female reproductive structures are common fossil elements from Cenomanian (ca 99–94 Ma) charcoal- and resin-rich beds of the Tupuangi Formation, Chatham Islands, southwest Pacific Ocean. Recent findings have proposed that these are the oldest fossil evidence of serotiny, a highly successful fire-adaptive reproductive strategy common among tree species living in fire-prone areas today. Herein, we systematically describe the external morphological and anatomical features of these fossils, by employing a combination of manual extraction and neutron tomography techniques. We propose a new species of conifer, Protodammara reimatamoriori, and a re-examination of fossil material of the Protodammara type species facilitated an emendation of the genus. Protodammara shares numerous features with extant Cunninghamia, Taiwania, Athrotaxis, and several extinct taxa of Cupressaceae, and is interpreted as an extinct lineage of the early-divergent ‘taxodioid Cupressaceae’ stem group. Chris Mays [chris.mays@nrm.se] Department of Palaeobiology, Swedish Museum of Natural History, Frescativägen 40, Stockholm 114 18, Sweden; School of Earth, Atmosphere and Environment, Monash University, 9 Rainforest Walk, Clayton, VIC 3800, Australia; David J. Cantrill [david.cantrill@rbg.vic.gov.au] Royal Botanic Gardens Victoria, Private Bag 2000, South Yarra, VIC 3141, Australia; School of BioSciences, University of Melbourne, Parkville, VIC 3010, Australia.