Deborah Painter (USA)
It’s all about time, rocks and residing issues. When people make makes an attempt to file the distant previous, there will probably be gaps in our information. Historians and archaeologists have the luxurious of the written phrase and of the preservation of tradition within the type of fences and aqueducts, of previous clothes, cash and monuments, in addition to radiometric relationship. They usually have the added bonus of carbon-14 relationship, helpful to instances going again roughly 60,000 years previously.
Gaps exist within the file preserved in sediments, however much more exist after we piece collectively the world earlier than people. Typically the entire historical past of a bunch of crops or animals will get recorded within the rocks, clay and silt and sometimes it does not.
We do have fossils of the earliest members of the family “tree” of elephants and of its side branches, the cousins which were not ancestors to our modern elephants. This success is more the exception than the rule. The fossil “record” of a group of living things is seldom that good. The fossil “record” is like a book, or another written record, but if it can be compared to a book, it is one with most of its pages ripped out.
Koolasuchus – a huge Australian amphibian
Sometimes, the absence of a family or group after a certain point in time makes us think the family disappeared, only to see their fossils again in younger rocks, after millions of years have passed. That is what happened with the Koolasuchus.
This amphibian’s name comes from the name Lesley Kool, a palaeontologist who prepared the fossils used by palaeontologists R. Jupp and Anne Warren, when they wrote a paper about the animal. Its fossil jawbone, skull roof bones and some other bones were discovered in Victoria, Australia beginning in 1986.
Koolasuchus was a “temnospondyl”, also known as a “labyrinthodont” amphibian, due to the folded pattern of the enamelled surface of its teeth that remind scientists of a maze or “labyrinth” (Fig. 1).
Temnospondyls included the biggest, heaviest four-legged land animals of the Carboniferous and early Permian, often reaching weights of 100kg (Fig. 2). Temnospondyls are regarded as the ancestors of reptiles. And they were all extinct by the early Jurassic period… or so the scientists thought.
Koolasuchus, a very large carnivorous fellow, showed up in the fossil record in the early Cretaceous, a time gap of about 45 million years. It was adapted to the cold woodland and wetland environment of ancient southern Australia and could hibernate in the coldest months, as most amphibians do today. It disappeared again from the fossil record in the early to mid-Cretaceous. Koolasuchus was temporarily lost in the fossil record, but is not forgotten by humans now – it is Victoria’s official fossil emblem.
The coelacanth fish
In December of 1938, Professor J. L. B. Smith of Rhodes University, South Africa, on holiday in Knysna, received his first description of a coelacanth fish and an urgent request to come to the East London Museum in the Eastern Cape of South Africa (Fig. 3).
He believed the specimen its young curator, Marjorie Courtenay-Latimer, described was a fossil that had somehow been preserved intact in the cold sea. It could hardly be anything else, since the coelacanths had all died out by the end of the Cretaceous period, 65 million years ago (Fig. 4).
However, it was quite alive, Courtenay-Latimer assured him:
It snapped at Captain Goosen’s fingers when he was touching it in the trawl net”.
The trawler Nerine had just brought it in as the day’s catch down at Irwin & Johnson’s Docks in the South African city of East London. The captain had a standing agreement with the Museum that Courtenay-Latimer could see their catch of the day to look for good museum specimens.
This day’s catch would go down in history. Since Professor Smith could not get to the museum immediately, and no one in East London was willing to put the big fish in their food storage or mortuary freezers, Courtenay-Latimer, and her assistant Enoch, had to skin and stuff it and preserve it with formaldehyde.
Smith later told the curator:
It is almost certainly a Crossopterygian allied with forms that flourished in the Mesozoic or earlier, but which have been extinct for many millions of years… to honor you for having got this wonderful thing I have provisionally christened it (to myself at present) Latimeria chalumnae.”
Newsreels projected onto movie theatre screens around the world hailed this incredible discovery.
Coelacanths’ closest relatives are the Australian, South American and African lungfishes. They look little like coelacanths, which are almost identical to their extinct freshwater relatives (Fig. 5). Crossopterygians are allies of the ancestors of amphibians and consequently all tetrapods that evolved from them. The motion of their fins is akin to the motion of walking. Lungfish have unusual tails, but lack the tail within a tail as seen in the coelacanths.
The history of the coelacanths was not seen in the rock record since their apparent extinction. It is probably because the coelacanths persisted in deep ocean waters following the Cretaceous period. Some had just gone to live in deeper waters of the Indian Ocean off East and Southern Africa, where only fishermen encountered them when they came up from the depths at night in search of food. They offered them for sale only for the fish oil trade, not knowing how unique they were.
Amazingly, in 1997 another species of Latimeria was well known only to Indonesian fishermen but not known outside the waters off the coast, and was discovered by scientist Mark Erdmann and his new wife, Arnaz, at a fish market. The current distribution of the genus is shown in Fig. 6.
Preserved specimens can be seen at various museums (Figs. 7 and 8).
The dawn redwood tree of China
Another chance discovery happened with the dawn redwood tree. During the World War 2 years, China was at war with Japan, one of the Axis powers. China was the ally of the United States. Botany professor T. Kan saw a strange tree in the central part of that country one winter day. It was an evergreen that, like bald cypresses, had shed its needles for the winter.
At its base was a small shrine, where people had been leaving offerings and lighting votive candles. Professor Kan knew he had seen an unusual tree, and he came back in spring and collected needles. Kan’s efforts were noticed by Zhan Wang, the director of China’s Central Bureau of Forest Research, and his colleague Hsen Hsu Hu, who realised that the mystery tree was a Metasequoia.
Scientists had thought this genus had disappeared in the Pleistocene epoch of the Quaternary Period, over one million years ago. Hu contacted his former professors at his old American college, Harvard University, where he had been the first Chinese scholar to earn a Ph.D. in botany from the university. The University paid for an expedition to collect live specimens to plant in their arboretum.
This was accomplished just before the politics between China and the United States went sour due to China’s new, post-World War II communist government. In the present day, the formerly rare Metasequoias grow in gardens and parks in China, Europe, and the Americas (Figs. 9 and 10).
So where does this leave us?
These three examples are of organisms that disappeared temporarily, geologically speaking, from the known fossil record for at least a million years. They remind us of the fact that we have not found all the fossils that exist, especially within the ocean floor sediments and rock layers.
References
Casane, Diedier, and Patrick Laurenti. Why coelacanths are not “living fossils”: a review of molecular and morphological data. 2013. BioEssays Journal volume 35: pages 332-338.
Gittlen, William.1998. Discovered Alive: The Story of the Chinese Redwood. United States: Pierside Publications. 166 pages.
Hu, H. H. 1998. How Metasequoia, the “living fossil”, was discovered in China. Arnoldia, Volume 58, number 4; pp.4-7.
LePage, Ben A., Christopher J. Williams, Hong Yang. 2005. The Geobiology and Ecology of Metasequoia. Netherlands: Springer. 434 pages.
Peschak, Thomas P. (2006). Currents of Contrast: Life in Southern Africa’s Two Oceans. Struik Publishing. 300 pages.
Popova, Maria. 2023. The Remarkable Story of the Dawn Redwood: How a Living Fossil Brought Humanity Together in the Middle of a World War. The Marginalian.
Smith, Margaret M. and Phillip C. Heemstra. (1986). Smith’s Sea Fishes. Springer-Verlag 1,047 pages.
Warren, A. A.; Hutchinson, M. N. 1983. “The last labyrinthodont? A new brachyopoid (Amphibia, Temnospondyli) from the early Jurassic Evergreen Formation of Queensland, Australia“. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences Volume 303: pp. 1-62.
Weinberg, Samantha. 2001. A Fish Caught in Time: The Search for the Coelacanth. Harper Collins 240 pages.
Whittaker, Jarrod. ABC News Australia, January 15, 2022.
Meet koolasuchus cleelandi, the people’s choice as Victoria’s official fossil emblem – ABC News
Whittaker, Kerry. 2014. Endangered Species Act Draft Status Review Report for the Coelacanth, Latimeria chalumnae. National Oceanic and Atmospheric Administration. 47 pages.
Yates, Adam. 2003. Guide to Wild Dinosaurs. United States: Sterling Publishing Company, Incorporated 255 pgs.
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