Top 10

These an­cient species have been evolv­ing longer than most.

Australian Geographic - - Contents - By Ellen Ryk­ers

CHARLES DAR­WIN COINED the term ‘liv­ing fos­sil’ in 1859, when writ­ing in On the Ori­gin of Species about platy­puses and lung­fish: “…these anoma­lous forms may al­most be called liv­ing fos­sils; they have en­dured to the present day, from hav­ing in­hab­ited a con­fined area, and from hav­ing thus been ex­posed to less se­vere com­pe­ti­tion.” It was never meant to be a sci­en­tific con­cept, rather a po­etic re­flec­tion on species with char­ac­ter­is­tics that first evolved long ago. But some sci­en­tists would rather aban­don the term, ar­gu­ing that it im­plies these flora and fauna have stopped evolv­ing. All species con­tinue to evolve, even if their changes aren’t ob­vi­ous to us.

The ‘liv­ing fos­sils’ listed here are not per­fect por­tals to pre­his­toric times. But they’ve sur­vived mass ex­tinc­tions, a dev­as­tat­ing comet im­pact and mul­ti­ple ice ages – while still ap­pear­ing roughly the same as their an­ces­tors did mil­lions of years ago.

1 WOLLEMI PINE Wollemia no­bilis

Wollemia trees were known only from fos­sils – some dat­ing back 200 mil­lion years – un­til 1994, when Na­tional Parks and Wildlife Ser­vices of­fi­cer David No­ble found un­usual trees in a re­mote Wollemi Na­tional Park gorge, north-west of Syd­ney. They matched fos­sil Wollemia, mak­ing them liv­ing relics from the age of di­nosaurs. The lo­ca­tion of the crit­i­cally en­dan­gered wild pop­u­la­tion is kept se­cret for the species’ pro­tec­tion, but cul­ti­vated trees are now avail­able com­mer­cially.

2 QUEENS­LAND LUNG­FISH Neo­cer­a­to­dus forsteri

Lung­fish date back at least 380 mil­lion years and fos­sils in­di­cate the Queens­land va­ri­ety has changed lit­tle for 100 mil­lion years. These long-bod­ied, olive-brown fish with pad­dle-like tails are na­tive to south-east Queens­land’s Mary and Bur­nett river sys­tems, but have been in­tro­duced else­where. While most fish breathe solely through gills, lung­fish are equipped also with a lung for breath­ing air at the wa­ter’s sur­face.

3 BROADGILLE­D HAGFISH Ep­ta­tre­tus cir­rha­tus

Hagfish are ocean-dwellers and this, the only species that in­hab­its Aus­tralian wa­ters, is found off the east coast. Like other hagfish, it ex­udes co­pi­ous slime from its skin that clogs the gills of preda­tors, al­low­ing it to es­cape. Only one hagfish fos­sil has been un­earthed, but it has a strik­ing re­sem­blance to modern hagfish. To­day’s fish have re­tained many char­ac­ter­is­tics from 300 mil­lion years ago.

4 ID­IOT FRUIT TREE Idiosper­mum aus­traliense

When cat­tle graz­ing around Cairns in 1970 sud­denly died, sci­en­tists found they’d eaten a poi­sonous fruit. The rain­for­est tree from which it had come turned out to be the sole sur­vivor of a group dat­ing back 120 mil­lion years, when flow­er­ing plants first evolved. Also called rib­bon­wood, the id­iot fruit tree’s an­cient lin­eage earned it the nick­name Green Di­nosaur. It oc­curs in only a few low­land for­est pock­ets, which might be ex­plained by its tox­i­c­ity. It’s thought the tree may rely on grav­ity (not an­i­mals) for seed dis­per­sal.

5 CREEP­ING STRAW­BERRY PINE Mi­cro­cachrys tetrag­ona

Tas­ma­nia is a conifer hotspot and an im­por­tant refuge for Gond­wanan relics such as the creep­ing straw­berry pine, an unas­sum­ing shrub named for its bright red ed­i­ble fruit. Fos­sil pollen grains dat­ing back 150 mil­lion years and 20-mil­lion-year-old fos­silised leaves from New Zealand in­di­cate that close rel­a­tives of this pine were once com­mon through­out the South­ern Hemi­sphere. Now the sole sur­vivor of its fam­ily, it’s found only in the rugged moun­tains of Tas­ma­nia.

6 MOUN­TAIN SHRIMP Anaspi­des tas­ma­niae

Tas­ma­nia’s Lake St Clair har­bours an­other Gond­wanan relic: the moun­tain shrimp. This crus­tacean is en­demic to the is­land state, where it’s com­mon in lakes and creeks 300m above sea level. Moun­tain shrimp re­sem­ble 250-mil­lion-year-old marine fos­sils. They had adapted to fresh­wa­ter habi­tats by 220 mil­lion years ago – ev­i­dent from NSW lake sed­i­ment fos­sils of shrimp that ap­pear iden­ti­cal to their modern Tas­ma­nian coun­ter­parts.

7 AUS­TRALIAN GHOST SHARK Cal­lorhinchus milii

In 2014 sci­en­tists an­a­lysed ghost shark DNA and dis­cov­ered its genome has re­mained largely un­changed for 420 mil­lion years. A bizarre-look­ing species with a trunk-like snout that it uses to sweep the sea floor search­ing for shell­fish, it cur­rently holds the ti­tle of ‘slow­est-evolv­ing ver­te­brate’ that we know of. De­spite its com­mon name, this is not a true shark. It’s part of the chi­maera fam­ily of car­ti­lagi­nous fish, which di­verged from sharks and rays 420 mil­lion years ago.

8 VEL­VET WORMS Ony­chophora

Aus­tralia’s 74 vel­vet worm species come from an an­cient lin­eage stretch­ing back half a bil­lion years. They are reclu­sive cater­pil­lar­like crea­tures that wad­dle on stubby feet in moist for­est un­der­growth, trap­ping prey by ex­pelling jets of sticky slime. Fos­sils are rare, but spec­i­mens have been found pre­served in 40–30-mil­lion-year-old am­ber and 300-mil­lion-year-old sed­i­ments. To­day’s vel­vet worms are strictly ter­res­trial, but a marine-dwelling rel­a­tive with very sim­i­lar mor­phol­ogy was un­earthed in a 500 mil­lionyear-old de­posit, dat­ing to the era when the ear­li­est an­i­mals be­gan to colonise the land.

9 PIG-NOSED TUR­TLE Caret­tochelys in­sculpta

Fos­sils of the pig-nosed tur­tle fam­ily Caret­tochelyi­dae dat­ing back to the Eocene (56–33.9 mil­lion years ago) are dis­trib­uted world­wide. To­day, just one species re­mains and it’s found only in re­mote rivers of NT and New Guinea. This an­cient, soft-shelled tur­tle is con­sid­ered an evo­lu­tion­ary link be­tween fresh­wa­ter and marine tur­tles, be­cause it in­hab­its rivers and yet sports pad­dle-shaped flip­pers more fit­ting to its sea-dwelling cousins.

10 STROMATOLI­TES Cyanobac­te­ria

No Aussie liv­ing fos­sil list would be com­plete with­out stromatoli­tes: un­re­mark­able stony clumps that dis­guise a re­mark­able his­tory. Com­posed of lay­ered mats of cyanobac­te­ria, stromatoli­tes are among the old­est liv­ing things known, with a fos­sil record linked to the dawn of life 3.7 bil­lion years ago. They were only known from an­cient fos­sils un­til liv­ing colonies were dis­cov­ered at WA’s Shark Bay in 1961. Stromatoli­tes were hugely sig­nif­i­cant in life’s evo­lu­tion on Earth. The tiny pho­to­syn­thetic bac­te­ria that make up these struc­tures pumped out so much oxy­gen they al­tered Earth’s at­mos­phere, paving the way for more com­plex life forms.











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