. . . the inevitable inference was that in this part of the world there had been a remarkable and unique degree of continuity between the life of over three hundred million years ago and that of only thirty million years ago.
—H.P. Lovecraft
In this passage from At the Mountains of Madness Lovecraft suggested that the ancient life of Antarctica may have remained unchanged for millions of years, perhaps unaffected by the several major extinction events that nicely carve up our geological time scale into the neat blocks we call “periods.” As absurd as this notion now is in the light of many new discoveries of fossils from Antarctica, which indeed testify that extinction events did occur globally, Antarctica (as the hub of Gondwana) may well have been a crucible for the evolutionary radiation of certain vertebrate groups. In this respect, if the earliest true sharks, called “neoselachians,” did originate here, as this chapter suggests, then Lovecraft's fictional hypothesis is not far from reality with respect to this one group. Sharks may well have had an evolutionary explosion in ancient Gondwana, reaching a rapid peak of evolution, then remaining unchanged for many hundreds of millions of years. Sharks only recently disappeared from the seas around Antarctica when the freezing polar conditions set in.
During the VUWAE 15 expedition, Gavin Young, then 26 years of age, collected an extraordinary fossil shark specimen from a small out-crop in the Lashly Ranges, about four kilometers from where we were camped near Mt. Crean. Lashly and Crean were both men on Scott's Terra Nova expedition who, with Lieutenant Evans, made up the return party which headed back to base after Scott and his men sledged
on to the South Pole. If not for the bravery and courage of Lashly and Crean, Evans would have surely perished after he developed scurvy and couldn't walk on any further. It is one of the great and often overlooked heroic stories of the early expeditions, well told in Evans' book, South With Scott, which he dedicated to Lashly and Crean. At the time this book was published, in the 1920s, it was the only popular written account of that expedition.
That small fossil shark that Gavin Young collected in 1971 became the holotype of a new genus that he described in 1982, naming it Antarctilamna prisca. It was also the oldest known shark in the world to have the cartilaginous braincase preserved. The shark was about half a meter long, with one rigid dorsal fin spine. Yet its most endearing feature is its teeth, which are decidedly odd in having three main cusps on each tooth, making it appear closely related to the much younger group known as the “xenacanths.” I desperately wanted to find more of this beast or other well-preserved shark remains from the same beds in order to shed some light on the mysterious affinities of this primeval shark. So, naturally, when we approached the Lashly Ranges and saw Mt. Crean peering down at us, I was once more fired up to go searching.
Unfortunately, the “A factor” kicked in again, and a fierce storm descended upon us that night. It eventually confined us to our tents for another three days before we dared to venture out near that sacred mountain of paleontological promise.
We woke up next day to temperatures of 1°F with strong winds gusting at 50 knots. It was way too windy to work outside, so we had to settle down to another long spell of waiting for the weather to clear up. I passed the time writing up some personal notes in my diary. One peculiar thing I noted for this day was that for the last three days while the weather was reasonably good I had been constipated, for the first time on the trip. I suspected that it might have been brought about possibly due to our now higher consumption of dehydrated foodstuffs. Fortunately the affliction ended, except that it was a damn inconvenience because of the blizzard raging outside to have to go and frequently answer calls of nature!
I spent that day reading more on the geology of Mt. Crean and pondering over my notes and map. That night we decided that we
would prefer to be pulled out from here on Friday, if given the option, rather than try to go on to Mt. Fleming. It was very cold and blowing hard outside. We recorded gusts of between 50 and 70 knots on our wind meter. I laid awake most of that night because of the incessant flapping of the tent, huddling deep inside my sleeping bags to try and get warm.
The next day saw little change in the weather. It was 1°F with very strong winds when I woke up. We were in the middle of a blizzard. The wind-chill factor outside was now very dangerous, so once more we were tent bound for the whole day. Even very short trips outside for calls of nature resulted in minor frostnip affecting my fingers. I slept in till almost noon, mainly because I'd been disturbed the previous night due to the howling noise of the winds.
I kept thinking how thin the canvas tent was, the sole thing that kept our frail human bodies from the ravages of the blizzard outside. My mind wandered back to a few days ago when we found the remains of a torn polar tent out near Mt. Metschel, and that if our tent suddenly ripped open we would have to make a dash for Margaret and Fraka's tent. The tents are made from very strong material, though, and both held out throughout the night without any damage. As we were the “glamour trip” of the season, Scott Base had let us take the newest tents and the best equipment available for our mission.
All day we read and played cards. After the evening meal I continued reading The Deptford Trilogy, and liked the book so much that I made a deal with him to swap it for a copy of my recently published Dinosaurs of Australia book. When I arrived back home in Australia I bought a copy from the bookshop, and as I was about to sign it for Brian I noticed that it had the front page in upside down, relative to the cover and the rest of the book. I signed it to him saying that this was the “special edition” for New Zealanders.
I anxiously looked outside next morning. Finally the wind had died down! It was sunny and clear, but still a bit chilly at −1°F. We decided that it was good weather to go out searching for fossils on Mt. Crean. After driving the skidoos across the glacier we pulled up at the base of the huge mountain. Getting up to the outcrops was not as easy as it had looked from back at camp as there were steep cliffs all around the
base of the outcrops where we wanted to search. Then we spotted a steep slough of ice and snow which had fallen down one side of the cliffs and which provided an access route onto the section where we wanted to work. Brian led us up to the outcrop by digging footholds in the ice wall with his pick. We put crampons over our boots, roped up and ascended the ice cliff in single file, using our ice picks to stabilize us at each step. Soon we were standing on the flat layers of Aztec Siltstone. We took off our climbing gear and started to fan out over the rocks, keenly searching for fossils.
It was one of the best days on the whole trip. We located the black shale layers found by earlier VUWAE parties and found some excellent fish fossils in them, including the tiny scales of the jawless thelodont fishes, and parts of articulated whole placoderms, rather than just isolated bones. My most exciting find from that level was a weird-looking lump of rock packed full of tiny white scales. Later I was to discover that it was a calcareous nodule full of many hundreds of thelodont scales that could be freed from the rock using weak acetic acid solution. As bone and teeth are made of phosphatic minerals, and limestone is made of calcium carbonate, weak acetic acid solutions will break down the rock but not affect the fossil materials, so after a few weeks of this treatment it is possible to free all the little scales as the rock dissolves so that they can be studied in perfect three-dimensional form. This was the first calcareous layer identified from the Aztec Siltstone to yield such magnificent preservation, not only of thelodont and acanthodian scales, but also shark's teeth, placoderm bones, lungfish tooth plates, and many other kinds of fossil fish remains.
Towards the top of the sequence I found some very well preserved specimens, including a rare articulated specimen of the placoderm Groenlandaspis showing the scale-covered tail. Later I discovered in the lab that this layer was also partly calcareous, enabling more bones to be acid-prepared out of the rock, making it another significant locality. By around 6:00 P.M. we had filled our backpacks with specimens and decided to call it a day.
Day 56 began unusually early for us. Brian and I woke up at 4:00 A.M. to listen for the Herc that was supposed to be flying over our area to check out the landing site, but no plane could be seen or heard. The
radio schedule at 8:00 A.M.told us that it was late and would be with us in an hour, but it didn't make it over to us at all that day. The weather was fine so we decided to make the most of it and do some more collecting.
We drove the skidoos over to a close-by outcrop where Gavin Young reportedly found the famous articulated specimen of Antarctilamna prisca, a section simply called “L1.” It is a narrow outcrop of rocks exposed up the otherwise ice-covered southern end of the Lashly Range.
Access to the outcrop was not as easy as it first looked. We had to rope up, attach our crampons and carefully negotiate a pathway through some small crevasses before we had even reached the base of the rocky bluffs. As with the previous day we had to cut ice steps to climb up the steep slopes. After an hour or so we were standing on marvelously flat terraces of light buff-colored sandstone and reddish mudstone that formed a series of wide steps all the way up the hill.
It was another very productive day of fossil collecting. We found two main layers rich in fish fossils. The lowermost layer was very soft, crumbly yellow sandstone that would fall apart in your hands with enough pressure. It was packed full of pure white fish bones, almost perfectly preserved, without any distortion or flattening. I found a few good skulls of the placoderm Bothriolepis with many isolated plates of Groenlandaspis and randomly scattered scales and bones of lobe-finned fishes. Higher up the section I discovered a gritty sandstone layer rich in small bits of fishes, including many well-preserved sharks' teeth.
One of the teeth I found at this second locality was very peculiar in having a wide broad base with two main cusps separated by a crenulated shearing edge. As I hit the rock to extract the little tooth (only about one centimeter wide) it literally jumped out of the rock into the sandy rubble. I got down on my hands and knees and eventually found the perfect white tooth, completely freed from the rock after 380 million years. Carefully I packed it in a small vial with some tissue paper and kept it safe in my top pocket for the rest of the day. A sketch of that bizarre-looking tooth in my notebook from that day is annotated stating “xenacanth sp. 2 new genus?” Indeed it was. Back in Perth after further study it became the holotype of the new genus, Aztecodus
harmsenae, meaning “Harmsen's Aztec tooth.” By splitting the rocks I found quite a lot of well-preserved sharks ' teeth from that layer, and many more when I got the samples back to the lab and could examine them under the microscope.
Already at that time an idea was taking shape in my mind that we had an exceptionally high diversity of fossil sharks present in the Aztec Siltstone. From this expedition we had mustered evidence of at least five different shark genera, maybe more. Previously, rocks older than Late Devonian had only yielded almost microscopic teeth of sharks, usually between one and four millimeters in total size, indicative of small sharks about half a meter or so in length. These older teeth were mostly from marine deposits, but here was evidence that sharks began invading freshwater habitats in Middle Devonian times, possibly for the first time in their history. Some of these ancient Antarctic sharks reached huge sizes for the Devonian, as the largest individual teeth of Portalodus suggest it had an estimated maximum size of up to three meters.
The first Devonian fossil shark's tooth found in Antarctica was recovered by geologists Bernie Gunn and Guyon Warren during their 1957 International Geophysical Year sledging expedition to the Skelton Névé region. They were primarily studying the igneous rocks in the region but still managed to bag a few good fossils. One specimen they found was a single tooth from the scree slope of Mt. Feather, which stands across from the Portal, towering 2985 meters high. The tiny tooth was sent to Dr. Errol White at the British Museum of Natural History in London, who established a new genus of shark based on that one bizarre tooth in 1968. He named it Mcmurdodus featherensis. The tooth was a jagged array of many flat, sharp cusps along a wide root. Nothing remotely similar to it had been found in any other Paleozoic shark.
However, about 20 years later a similar tooth turned up from the remote deserts of central Australia. Dr. Sue Turner of the Queensland Museum, working with Gavin Young, described it as a new species of the Antarctic genus Mcmurdodus. In their paper they put forward a radical idea at the time that these teeth were very advanced in their structure because they possess a hard outer enameloid made of several
overlapping layers, a feature that characterizes modern sharks or neoselachians. Up until that find the oldest known neoselachian was a small shark named Anachronistes from the early Carboniferous of England, around 345 million years old. The new finds of Mcmurdodus pushed the origin of this group back by another 40 million years.
In 1995 I once more made the sacred pilgrimage of all paleontologists to the Natural History Museum in London and searched among the many rows of cabinets full of fossil fishes until I'd located the drawer labeled “Mcmurdodus.” I spent some time examining and drawing the little shark's tooth from Mt. Feather. It was only about four millimeters wide and parts of the main cutting edge were broken, but the cusp shapes could be accurately restored with reasonable confidence from what was left.
At the time I was hot on the trail of evidence of any older sharks, and to determine for myself whether the earlier published records of fossil sharks were based on reliable data. The oldest true fossil sharks' teeth at that time were tiny specimens from Spain named Leonodus. Nobody doubted these were sharks' teeth, as they had two curved cusps and a well-developed root. Other Early Devonian teeth had been found from Saudi Arabia, and after examining these specimens in the Natural History Museum collections, I was convinced that they also represented several different species of early sharks. However, I also examined some other problematical specimens from the Early Devonian of Canada, first described as belonging to acanthodian fishes (named Doliodus), and discovered that they were really sharks' teeth as well.
The interesting link was that the north of Spain and most of Saudi Arabia had actually been part of the northern margin of Gondwana during the Early Devonian. The Canadian specimens may also have belonged to a separate block of crust, called the Alexander Terrane, which was closer to Gondwana at the time than to North America or Europe. The story was starting to jell. Sharks had probably arisen in Gondwana perhaps in the warm tropical seas off its northern coasts, and then they underwent a great radiation and diversification at the start of the Middle Devonian, about 385 million years ago. The first good evidence of this explosion of shark biodiversity was therefore the sharks' teeth fauna found in the Aztec Siltstone of Antarctica and from
central Australia. Here was the pointer to the birthplace of all sharks, the very crucible of their evolution.
By the latter part of the Middle Devonian and Late Devonian sharks rapidly became ubiquitous. Although mostly known from isolated teeth, scales, and spines, at least 50 different species of sharks are known by the close of that period some 355 million years ago. From that point on sharks radiated into many different groups, with specialized descendants like the rabbit fishes (holocephalans) and flattened rays. Today we know of approximately 800 living species of chondrichthyans.
My long field season of working in Antarctica's remote wilderness had now come to an end. At around 6:00 P.M. we trudged back slowly to the skidoos, carefully tracing our steps around the crevasses, backpacks laden once more with the heavy spoils of our hunt. We had found many new species of fossil fishes, fossils which would now be put to good use back in Australia by contributing to solving problems of global plate tectonics, past climates, and age correlations right across the broad realm of Gondwanan countries. Inwardly, I felt quite pleased that the whole trip had gone well scientifically, but as we headed off back to our little yellow pyramid tents in the distance, I knew that our work was not yet over until our specimens were safely back at Scott Base.
That evening our 8:00 P.M. radio schedule informed us that VXE-6 was planning a recon trip over to us the next morning. If they were not happy with the potential for landing a Herc on the ice we would have to try to get two New Zealand Air Force helicopters to pull us out. At this stage, because an airlift was so crucial to getting all of our specimens and equipment out in one go, we were told to report back with weather conditions to Scott Base every six hours from then onwards.
That night Brian and I joked about how we could lure a Herc down to pick us up. We concocted a somewhat silly advertisement that could be broadcast to any approaching plane. We were both delirious over it, laughing uncontrollably, although this may have been due to other factors acting on us at the time. So, anyhow, I wrote the whole inane conversation down in my notebook. In the interest of future psychiatry students studying the mental health of deep field expeditioners, here it is:
Hey guys, it's Bingo Night down here at the Lashly Glacier—Free Parking—Don't forget about our special this week—a Free Lunch—succulent turkey, a big super deluxe block of chocolate, barley sugar, and hey, guess what? We've just had ourselves a bit of a whip around! Yessiree, we've got a big hat full of greenbacks—just a few bucks for you guys that work soooo hard for VXE-6.
Now, why don't you come down here—right now! This glacier's smoother than a baby's arse—why you could land a C5 here no worries!
It's Pick-Up and Pullout time for K221 and Drop-Down and Collect Time for XRDs!
Hey! It's Hootenanny Night down here on the Lashly Glacier! Going to McMurdo? We're pretty friendly down here—we've got some good lookers that want to go all the waaay!
As the diatribe shows we were really quite silly by this stage and even discussed in detail the merits of the C-130 Cargo Cult, suggesting that we needed to build a full-scale C-130 out of snow and place it down at the start of the ice runway to appease the fussy gods of VXE-6. Needless to say, I slept very well that night, still chuckling to myself from deep within the confines of my two sleeping bags. Brian awoke every six hours and radioed back details of the weather.
Our last full day in the field was Friday, 10 January 1992. The weather was fine, clear and sunny with almost no wind, but a brisk −1°F. Visibility was excellent, we could see for about 30 kilometers, and there were only a few wispy cirrus clouds loafing around a very bright blue sky. The plan for the day was to pack up and prepare for the pickup, plus to make regular weather reports to base. At 10:00 A.M.the temperature plummeted to −6°F. The Herc was due to arrive at 11:00 A.M.but was delayed. We decided to pack up our base camp and move out to the middle of the Lashly Glacier to facilitate the pick-up.
That afternoon Brian and Fraka drove the skidoos up and down the middle of the glacier for about an hour to flatten out a runway area for the Herc. Anything at all that we could do to entice them down to an easy, safe landing was worth a try, according to both Brian and Margaret's past experiences of many delayed pick-ups. The runway they made that day was about ten meters wide by a kilometer long and looked so good that you'd have thought a jumbo jet could land safely
on it. How deceptively perfect it looked! Little did we realize then the problems that runway would soon cause us.
Herc XRD-04 came droning overhead about 4:40 P.M.It did a quick fly-past, and the crew chatted to us on the radio for a short while. They seemed to be very happy with our landing strip so planned to return early the next morning for our pick-up at around 8:00 A.M., provided the weather was fine.
From here on we were instructed to give four-hourly weather reports back to Scott Base, followed by hourly reports throughout the night. That evening Fraka cooked what we hoped would be our last supper in the field, a dehydrated beef curry with soup, peas, and other dried vegetables. We were all very excited by the prospect of going back to Scott Base and the luxuries of civilization, but were inwardly doubtful of actually being picked up on time. Usually there are delays for at least one or two weeks, as exemplified by Margaret's experience on the Darwin Glacier in the 1988-89 season. However, if the good weather would hold out for one more day we just might actually get pulled out on time. We never gave up hope of something actually happening according to schedule, as for example our navigating the Mulock Glacier, which went ahead right on time.
The fine weather continued that night, but it also had its downside, as it became uncomfortably cold. I recorded our coldest temperature for the whole trip on that very last night. At 3:00 A.M.I popped my head and upper body out of the tent and spun the thermometer around for a full minute, as was the routine practice. The sky was still quite clear with about three-eighths cloud cover and the air temperature was −18°F. I grabbed a few hours of intermittent sleep, occasionally waking to hear Brian's hourly weather reports.
On the morning of 11 January, at 5:00 A.M., it had “warmed up” to −9°F. The sky was amazingly clear, not a cloud to be seen anywhere, and no wind. Sunshine was belting down on us. It was perfecto mundo for a Herc landing!
I was full of hope that we would be going back to Scott Base that day.