Diverse bryophyte mesofossils from the Triassic of Antarctica

Abstract

Compared with the fossil record of vascular plants, bryophyte fossils are rare; this circumstance is probably related to a lower preservation potential compared with that of vascular plants. We searched for bryophyte remains in extensive collections of plant‐fossil assemblages from the Triassic of Antarctica and identified three assemblages with surprisingly well‐preserved bryophyte fossils. Although most bryophyte remains are too fragmented to conclusively place them in a detailed systematic context, they exhibit features sufficient to suggest the presence of at least four types of leafy bryophytes and two orders of thallose liverworts (Pallaviciniales and Metzgeriales) in the high‐latitude Triassic ecosystems of Antarctica. The leafy bryophytes exhibit combinations of morphological features (e.g. keeled and entire‐margined, ecostate leaves with elongated cells) that today occur in only a few small, systematically isolated groups, but were common among Palaeozoic and especially Mesozoic bryophytes. The diverse morphologies of the bryophyte fossils add further support to previous hypotheses that during warmer periods in the Earth's history, bryophyte vegetation may have been particularly rich and diverse in high‐latitude regions. Through analysis of the sedimentology and taphonomy of these assemblages, we identify a combination of key factors that may explain the preservation of bryophyte fossils in these deposits: (1) punctuated, high‐energetic sedimentary events causing traumatic removal and incorporation of bryophytes into sediment‐laden flood waters; (2) limited transport distance, and short period of suspension, followed by rapid settling and burial as a result of a rapidly decelerating flow discharging into a floodplain environment; and (3) early‐diagenetic cementation with iron hydroxides in locally anoxic zones of the organic‐rich, muddy substrate.

South African Lagerstätte reveals middle Permian Gondwanan lakeshore ecosystem in exquisite detail

“…The thallose liverworts reported here (Fig. 4j ) are one of only a few records from the Permian of Gondwana 54 , and are the first from the Permian of Africa.…”

Rare Carboniferous and Permian glacial and non-glacial bryophytes and associated lycophyte megaspores of the Paraná Basin, Brazil: A new occurrence and paleoenvironmental considerations

“…However, the high abundance of the bryophytes, their good preservation without strong fragmentation, the presence of a very fragile probable lateral sporophyte and the abundant megaspores evidence very proximal and shallow depositional settings instead (cf. bryophyte taphonomy in Bomfleur et al, 2014). The plants must have not been transported as bedload but in slow, fluctuating water flows and deposited in very calm conditions.…”

“…The presence of Botryoccocus and the apparent lack of acritarchs in the rhythmite of Salto 1 (Longhim et al, 2002) does not necessarily point to a lacustrine paleoenvironment; a palynofacies analysis is recommended. Bomfleur et al (2014) emphasized that the preservation of bryophytes usually requires rapid burial to inhibit chemical decay and destruction by organisms, but this premise can only partly be extrapolated to the Itarar e Group. Firstly, it is necessary to bear in mind that plants lying on the floor of cold water environments are (1), (2), (3), (4), and (6) Gametophytes with phyllotaxis in spiral, lanceolate phyllides, with amplexicaulis bases, and acute tips.…”

“…Dwykea in Dwyka group, South Africa Dwykea araroii of the Itarar e group (this study) diversified in the shaded, warm and humid areas of the understory of the Glossopteris vegetation, but they must have been destroyed by exposure to chemical and microbial decay as well as during transport and mixing with more resistant vascular plants. For example, Bomfleur et al (2014) found only very small bryophyte fragments (<1 cm long) mixed with other fossil phyllids in Triassic floodplain and crevasse-splay deposits in Antarctica and commented that other probable bryophytes occur as abundant but unrecognizable very small organic fragments.…”

New Bryokhutuliinia species (Bryophyta) with sporophytes from the Upper Jurassic of Transbaikalia

“…Muscites brickiae Moisan, Voigt, Schneider & Kerp from Kyrgizia (Moisan et al, 2012) has a rather similar habit, but differs in the smaller size and total absence of a leaf border. Unnamed leaves from the Antarctic (Bomfleur et al, 2013, Fig.2) have a somewhat similar cell shape, leaf border and laxer areolation towards the base, but the leaves are shorter and the cells are larger. * * * Ignatov & Shcherbakov (2011) already noted that fossil mosses often occur as single plants.…”