Feeds

Wedding tackle started out as PROTO-SHARKS' LEGS, boffins say

Cut me off at the knees and call me a tripod

Application security programs and practises

Researchers from Australia and the UK have taken a look back over the fossil records of placoderms - an early type of armoured fish - and come up with a startling suggestion: some of the earliest male genital organs known to palaeontology started out as a kind of “legs”.

Well, not quite legs, since placoderms were aquatic: rather, what the researchers have concluded in their study was that their organs, referred to as “claspers” because of the creatures' reproductive habits, started out as paired appendages rather than (as in sharks), modified single fins.

Placoderms were predators – the world's first megapredators, two of the researchers (Flinders' John Long and Curtin's Kate Trinajstic) explain at The Conversation, here. They existed for 70 million years, becoming extinct 360 million years ago, and the largest reached the size of a modern great white shark.

They're also the earliest creatures known to have evolved copulation (instead of spawning into the water), which adds spice to the interest science shows in them.

It's the detail of that copulation that the researchers, from Curtin University, the Western Australian Museum, Monash and Flinders Universities, the Australian Synchrotron, and the Natural History Museum in London have drilled into.

What they've found challenges the long-held assumption that male sex organs' evolution broadly mirrored that of the shark, in which a fin evolved to become the clasper that impregnated the female.

Placoderm mating

Placoderms' probable mating style. Image: John Long, Flinders University

“Unlike the claspers of modern sharks and rays that are a part of the paired pelvic fins, the claspers and female basal plates in placoderms were not at all connected to that fin,” Long and Trinajstic write. “Instead they developed as an extra pair of limbs further down the body.”

Further: “The claspers in placoderms can now be regarded as a serial homologue or gradual development of the other paired appendages - an extra pair of legs, so to speak.” ®

Build a business case: developing custom apps

More from The Register

next story
Asteroid's DINO KILLING SPREE just bad luck – boffins
Sauricide WASN'T inevitable, reckon scientists
BEST BATTERY EVER: All lithium, all the time, plus a dash of carbon nano-stuff
We have found the Holy Grail (of batteries) - boffins
The Sun took a day off last week and made NO sunspots
Someone needs to get that lazy star cooking again before things get cold around here
Boffins discuss AI space program at hush-hush IARPA confab
IBM, MIT, plenty of others invited to fill Uncle Sam's spy toolchest, but where's Google?
Famous 'Dish' radio telescope to be emptied in budget crisis: CSIRO
Radio astronomy suffering to protect Square Kilometre Array
Bad back? Show some spine and stop popping paracetamol
Study finds common pain-killer doesn't reduce pain or shorten recovery
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
Application security programs and practises
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
Securing Web Applications Made Simple and Scalable
Learn how automated security testing can provide a simple and scalable way to protect your web applications.