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Chaloner, WG

Kenrick, P

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11Did Captain Scott's Terra Nova Expedition Discover Fossil Nothofagus in Antarctica?Professor Bill Chaloner FLS1 and Dr Paul Kenrick FLS21.   Dept. of Earth Sciences, Royal Holloway, University of London TW20 0EX2.     Dept. of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BDe1: W.Chaloner@rhul.ac.uk e2: p.kenrick@nhm.ac.ukOne of the great palaeobotanical “discoveries” of the last century was the fi nding of fossil leaves of the Permian gymnosperm Glossopteris by Captain Robert Falcon Scott ’s ill-fated Terra Nova Expediti on (or Briti sh Antarcti c Expediti on) to Antarcti ca in 1910–12 (Fig 1). The leaves were collected from a fallen block on the Beardmore Glacier, when the party were on their return from the South Pole, and although they were apparently unaware of its identi ty or palaeobotanical signifi cance, they carried the specimens as part of the load on the sledges that they were towing by hand. The material was subsequently found, beside the tent in which they had fi nally succumbed, and brought back to Britain, where it is now housed in the Natural History Museum, London (Anon. 2008). The descripti on of the fossil plants was fi rst assigned by the Trustees of the museum to EA Newell Arber, the demonstrator in palaeobotany at Cambridge University, but just as his results were about to be published, he unexpectedly raised strong objecti ons to editorial changes, and the manuscript was withdrawn (Riff enburgh 2010). The work was reassigned to AC Seward FRS, a leading palaeobotanist and the Professor of Botany at Cambridge. Seward described and illustrated the material, promptly publishing a detailed analysis (Seward 1914). Both Newell Arber and Seward came to essenti ally similar conclusions. Glossopteris has long been recognised as one of the most disti ncti ve and signifi cant components of the Permian fossil plant record from the ancient southern-hemisphere Fig 1 Captain Robert Falcon Scott , second from right, on the Terra Nova ExpeditionTHE LINNEAN VOL 31(2) OCT 2015Images: Glossopteris images © The Trustees of the Natural History Museum, London12conti nent of Gondwana (Du Toit 1937) (Fig 2A). Even before its true character and systemati c status were established, the distributi on of the genus, based on leaves alone, was a classic of the disjunct distributi ons of both plants and animals produced by the breakup of Gondwana. Before its discovery by Scott  in Antarcti ca, it was known from abundant material from South America, South Africa, India and Australia—the present-day components of the Palaeozoic superconti nent Gondwana. It is perhaps appropriate to briefl y introduce an added dimension to the story, relati ng to Marie Stopes FLS, the family planning pioneer and author of Married Love (Stopes 1918; Rose 2007). At the ti me Marie Stopes was a lecturer in palaeobotany at the University of Manchester and at the peak of the palaeobotanical phase of her career (Chaloner 2005). She met with Scott  shortly before the Terra Nova Expediti on to Antarcti ca. In her memorable textbook of palaeobotany, Ancient Plants, published coincidentally in 1910, Marie Stopes wrote of Glossopteris: “A fossil fl ora which has aroused much interest, parti cularly among geologists, is that known as the Glossopteris fl ora.” She goes on to say that this fl ora is “characteristi c of the Permo-Carboniferous period in the regions in the southern hemisphere now known by the names of Australasia, South Africa, and South America, and in India. These regions, Fig 2 Leaves and leaf fragments of Glossopteris (Permian Period). Arrows indicate the leaf midribs. A. Whole feather-like leaves of Glossopteris browniana, Nagpur, India. Scale Bar = 3.0 cm. NHMUK V64045. B. Overlapping leaf fragments of Glossopteris indica collected from the Beardmore Glacier (Buckley Island), Antarctica, by the Polar Party, Terra Nova Expedition, February 1912, NHMUK V13451. Scale Bar = 1.5 cm. C. Details of part of leaf from B. Mesh of anastomosing veins characteristic of Glossopteris are clearly visible between two leaf midribs (arrows). Scale Bar = 0.5 cm. Specimen photographed using illumination by cross-polarised light to enhance organic component.ACB13at that date, formed what is called by geologists ‘Gondwanaland’” (Stopes 1910). Interesti ngly there is no menti on of Antarcti ca there; for in his biography of Marie Stopes, Keith Briant (1962) describes the meeti ng between her and Captain Scott  while he was making a fund-raising tour to support his projected second Antarcti c expediti on. Briant reports that at a lunch in Manchester when they met, she tried to persuade him to take her (and his wife) to Antarcti ca, “where she might make valuable palaeontological discoveries on the subject of coal”. Although Scott  did not accept this propositi on he “later visited her at the university to familiarize himself with the look of the fossils; and when he was found dead in the Antarcti c there were discovered near him some pieces of fossil plants” (Briant 1962). Alas, we do not know what fossil plants Marie Stopes showed to Scott  on that occasion—did she show him any Glossopteris specimens from other Gondwanan sources? Was that indeed the focus of her interest there…or was she perhaps hopeful of early angiosperm fossils, another subject of her enthusiasm that ti me? We don’t know, but it seems that Scott  did not come away from the meeti ng with a sharp image of what characterises Glossopteris leaves, for when they made that remarkable discovery, the identi ty of those leaf fragments went unrecognised.The fi rst fully documented account of Antarcti c Glossopteris is in Seward’s “Antarcti c Fossil Plants” (Seward 1914). This account covers the fossil plant material from Scott ’s fi rst expediti on, Ernest Shackleton’s 1908 expediti on, but most parti cularly Scott ’s second and fi nal (Terra Nova) Expediti on. Here we have an account of the Glossopteris material collected by Scott  and Wilson in February 1912. This was one of two important fossil plant discoveries made on Scott ’s return journey from the pole, on two successive days, 8–9 February. Seward records: In his journal on February 8th, Captain Scott  wrote ‘We lunched at 2 well down towards Mt. Buckley the wind half a gale and everybody very cold and cheerless. However, bett er things were to follow…. The moraine [rock debris lying on the glacier surface] was obviously so interesti ng that when we advanced some miles and got out of the wind I decided to camp and spend the rest of the day geologising ….. we found ourselves under perpendicular walls of Beacon Sandstone weathering rapidly and carrying veritable coal seams. From the last Wilson, with his sharp eyes, has picked several pieces of coal with beauti fully traced leaves in layers. (Which, Seward adds in parenthesis, were Glossopteris indica, of which he published descripti ons and photographs.) But other fossil leaves were found the following day, as is recorded in Wilson’s own diary (King 1972): “Fri. 9 Feb, 1912: — We made our way along down the moraine and at the end of Mt. Buckley unhitched and had half an hour over the rocks and again got some good things writt en up in sketch book.”In a page dated 9 February of his sketch book, reproduced in King’s account (p 241), he writes: THE LINNEAN VOL 31(2) OCT 2015Image:  Nothofagus image courtesy J Francis14Some of the weathered blocks which we found on the moraine were of good burning shiny crystalline coal – but most of it was shaly, lignite or slaty. …..But the best leaf impressions and the most obvious were in the rott en lumps of weathered coal which split up easily to sheath knife and hammer. Every layer of these gave abundant vegetable remains… Seward conti nues that quotati on from Wilson’s notes: “Most of the bigger leaves were like beech leaves in shape and venati on. In size, a litt le smaller than Briti sh beech and the venati on much more abundant and fi ner in character, but sti ll disti nctly beech like.” Clearly these were totally diff erent from the Glossopteris leaves collected the previous day. No one could describe the Glossopteris leaves brought back from Scott ’s expediti on as being “beech-like”. Following this quotati on from Wilson’s diary, (writt en the day aft er he had collected what Seward had identi fi ed as Glossopteris indica, 8 February) Seward goes on to say, “…on the surface of the carbonaceous shale pieces of Glossopteris- leaves are clearly shown: these are the beech-like impressions referred to in the diary”. But one has to ask—how did Seward know that it was Glossopteris leaves that Wilson was describing? The Glossopteris material that Seward studied, now in the Natural History Museum, London (NHM), is not remotely like beech. We cannot believe that the material that Wilson described as “disti nctly beech-like” was Glossopteris. Wilson was unquesti onably a criti cal observer as well as a highly competent naturalist with an arti st’s eye for detail (Seaver 1937; Williams 2008) and indeed had familiarity with our beech, Fagus sylvati ca and hence his remark. So we have the intriguing mystery —what were the “beech-like leaves” seen by Wilson and reported in his diary? They were seen on 9 February (1912) a day aft er the Glossopteris leaves described by Seward, but no material or sketches of them appear to exist, nor to our knowledge were any of these beech-like leaves collected by Scott ’s party. It is important at this point to accept that all the plants brought back from Scott ’s expediti on were collected from loose material on the moraine surface, and not from the cliff s of Beacon Sandstone. Newell Arber, in his unpublished report on the Terra Nova material, wrote “all the plant-specimens have been obtained from moraine material scatt ered abundantly on the face of the glacier and were not in situ”.The most obvious—and appealing—possibility is that Wilson had encountered fossil leaves of Nothofagus, the Southern Beech (Fig 3). Nothofagus leaves are indeed Fig 3 Leaves of Nothofagus collected from Sirius Group sediments in the Transantarctic Mountains (Dominion Range) (late Pliocene–Early Pleistocene). Scale Bar = 1.0 cm. 15beech-like (and hence of course the choice of the generic name—based on Fagus, the Beech of the northern hemisphere—and both genera may be regarded as members of the same family, Fagaceae s.l., although many botanists now place Nothofagus in a closely related but separate family, the Nothofagaceae). Wilson’s “beech like” leaves would of course have been far younger than the Permian Glossopteris, indeed probably of Pliocene age, as is the material of that species described by Francis and Hill (1996) from the Beardmore Glacier.Fossil leaves of Nothofagus have been reported, together with wood and pollen from a number of Cretaceous and Terti ary localiti es in Antarcti ca over the last 20 years [see Hill et al, (1996) and Francis and Hill (1996) and a broader review in Cantrill & Poole (2012)]. Its signifi cance in relati on to the breakup of Gondwana and the resulti ng disjuncti on of plant distributi on is quite comparable to that of Glossopteris. As stated by Swenson et al (2001): “The Austral biota reveals many links between Australia and South America that have challenged biogeographers for many years. Nothofagus, the Southern Beech is probably the classical example” (Fig 4). However, in a recent paper Christenhusz and Chase (2013) questi on the role of conti nental movement (plate tectonics) in explaining the widely-separated occurrences of certain southern-hemisphere genera such as Nothofagus. They suggest that “…families with a crown age appropriate to be explained by plate tectonics did not seem to have distributi ons indicati ng an involvement of long-distance dispersal, but the advent of molecular systemati cs and molecular clocks has shown this to be otherwise”. They go on to say that “the stem group of Nothofagaceae, for instance, is certainly old enough to have been widespread before the breakup of Gondwana (up to 95mya) but Cook and Crisp (2005) esti mate the crown group to be too recent and the sequence of break up of conti nental areas does not fi t relati onships of the clades in Nothofagus”. However, Cook and Crisp do accept that “the molecular dates for the divergences of Australasian and South American taxa are consistent with the rift ing of South America from Antarcti ca”. So, a modern reading of the biogeography of Nothofagus is complex suggesti ng possibly a signifi cant role for dispersal, but this is not universally accepted (Heads 2006; Cantrill & Poole 2012). Fig 4 Distribution of Nothofagus: fossils (continuous line including the Ninety East Ridge and Antarctica), extant distribution solid black and main massings (extant and fossil plus extant) of the four extant subgenera. With permission from Heads 2006, Fig. 1.THE LINNEAN VOL 31(2) OCT 201516Professor Jane Francis (Director of the Briti sh Antarcti c Survey) published on Nothofagus leaves from Neogene Sirius Group sediments that outcrop on the other side of the Beardmore Glacier (Francis & Hill 1996). This Neogene fl ora is parti cularly signifi cant for what it tells us about the geologically recent climati c deteriorati on in Antarcti ca. It documents a short interlude of relati ve warmth within the general cooling trend that saw ice sheets retreat temporarily to within 500km of the South Pole (Cantrill & Poole 2012). It also provides evidence for the fi nal stages of ecosystem collapse, when glacier advance destroyed the last vesti ges of higher plant communiti es. She wrote (in an e-mail to WGC, 19 September 2012):I am prett y convinced that the ‘beech-like’ leaves that Wilson saw were most likely Nothofagus from Neogene boulders in moraines. The Sirius Group rocks are glacial ti llites with layers of periglacial outwash sediments sandwiched within them, which must have been land surfaces adjacent to retreati ng glaciers colonised by small, dwarf bushes of Nothofagus. It is highly likely that there might be boulders of this sediment on the other side of the Beardmore because Sirius Group sediments are plastered all along the walls of the Beardmore valley. It will probably be impossible to prove that Wilson and Scott  actually saw Nothofagus leaves but I totally agree that the specimens of Glossopteris from Scott ’s expediti on look nothing at all like beech leaves.This leaves us with a puzzle. If Wilson did observe Nothofagus on the Beardmore Glacier, why did he not collect these specimens too, extending the collecti ons of the previous day? Perhaps there was just too litt le ti me and there were more pressing issues on his mind. On 8 February,  they spent an aft ernoon collecti ng and had an evening to consider their fi nds. On 9 February, when the beech-like leaves were recorded, they stopped for only half an hour. Wilson writes, “We made our way along down the moraine and at the end of Mt. Buckley unhitched and had half an hour over the rocks and again got some good things writt en up in sketch book” (King 1982). We must also remember that at this ti me they were under severe conditi ons of mental and physical strain, with three of the party injured. Wilson was sti ll limping from the eff ects of a badly strained tendon. Only three days later Scott  records, “We are in a very criti cal positi on” (Seaver 1937). Professor Jane Francis (email 5 February 2015) has made this very perti nent comment on the apparent lack of any fossil leaves collected by the party: “The Nothofagus leaves on the other side of the Beardmore Glacier are preserved in a very fi ne-grained sedimentary matrix that breaks up very easily, so any Nothofagus leaves may have disintegrated aft er collecti on.” On the available evidence it certainly looks as though Scott ’s Terra Nova expediti on made not one but two very memorable palaeobotanical discoveries. If our interpretati on of Wilson’s “beech-like leaves” is valid, then Scott ’s party were the fi rst to discover the Antarcti c occurrence of two iconic southern hemisphere plant genera, Glossopteris and Nothofagus. One hundred years on from that ill-fated expediti on, there are numerous records of both genera from the Antarcti c conti nent (Cantrill & Poole 2012).17REFERENCESAnon. 2008. Treasures of the Natural History Museum. London: The Natural History MuseumBriant K. 1962. Marie Stopes, a Biography. London: Hogarth PressCantrill DJ & Poole I. 2012. The Vegetati on of Antarcti ca through Geological Time. Cambridge: Cambridge University PressChaloner WG. 2005. The palaeobotanical work of Marie Stopes. Geological Society Special Publicati ons 241: 127–135Christenhusz MJM & Chase MW. 2013. Biogeographical patt erns of plants in the Neotropics—dispersal rather than plate tectonics is most explanatory. Botanical Journal of the Linnean Society 171(1) 277–286Cook LG & Crisp MD. 2005. Not so ancient: the extant crown group of Nothofagus represents a post-Gondwanan radiati on. Proceedings of the Royal Society, London B 272: 2535–2544Du Toit SL. 1937. Our Wandering Conti nents. Edinburgh: Oliver & BoydFrancis JE & Hill RS. 1996. Fossil Plants from the Pliocene Sirius Group, Transantarcti c Mountains: Evidence for Climate from Growth Rings and Fossil Leaves. Palaios 11: 389–396Heads M. 2006. Panbiogeography of Nothofagus (Nothofagaceae): analysis of the main species massings. Journal of Biogeography 33: 1066–1075Hill RS, Harwood DM & Webb PN. 1996. Nothofagus beardmorensis (Nothofagaceae) a new species based on leaves from the Pliocene Sirius Group, Transantarcti c Mountains, Antarcti ca. Review of Palaeobotany and Palynology 94: 1–24King HGR. 1972. Diary of the Terra Nova Expediti on to the Antarcti c 1910–1912. London: Blandford PressKing HGR (ed.). 1982. South Pole Odyssey—Selecti ons from the Antarcti c Diaries of Edward Wilson. Cambridge: Scott  Polar Research Insti tuteRiff enburgh B. 2010. The science of Captain Scott ’s Terra Nova Expediti on 1910–13: a report on the Scott  Exhibiti on Research Project of the Natural History Museum and the Scott  Polar Research Insti tute. London: Natural History Museum. 220Rose J. 2007. Marie Stopes and the sexual revoluti on. Stroud, Gloucestershire: TempusSeaver G. 1937. Edward Wilson: nature-lover. London: John MurraySeward AC. 1914. Antarcti c fossil plants. In: Briti sh Antarcti c (“Terra Nova”) expediti on, 1910. Natural History Reports Geology 1, 1. London: Briti sh Museum (Natural History): 1–49Stopes MC. 1910. Ancient Plants. London: Blackie & Son Stopes MC. 1918. Married Love. London: A.C. Fifi eldSwenson U, Hill RS & McGloughlin S. 2001. Biogeography of Nothofagus supports the sequence of Gondwana break-up. Taxon 50, 1025–1041Williams I. 2008. With Scott  in the Antarcti c—Edward Wilson, Explorer, Naturalist, Arti st. Stroud: the History Press Ltd

Did Captain Scott's Terra Nova Expedition discover fossil Nothofagus in Antarctica?

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Did Captain Scott's Terra Nova Expedition discover fossil Nothofagus in Antarctica?

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