Monday, September 29, 2014

Meet the Kardashian family of the fossil world

Hallucigenia, my bestie.
Remember this weird little dude, Hallucigenia, who lived about 500 million years ago?

He's so freaky that scientists can't place him in a family tree with any other animals -- they don't even know which end is his head and which is his rear. Oh, Hallucigenia, you oddball, orphaned critter with a mysterious butt, I love you truly.

But wait. What's this I hear? Some scientists have just discovered its family tree! Turns out Hallucigenia has two living relatives, who also happen to be among the most lovable and preposterous creatures on our planet. Hallucigenia is related to:

1. Velvet worms
In some species, the male puts some sperm
onto the female's back, then the sperm
melts her skin to get inside her body.
Ouch, tough break for the ladies.
OK, get this. Turns out Hallucigenia's legs each ended in a kind of foot with two opposing claws. These claws later evolved to form the mouth of today's velvet worms.
Yes, that said mouth. Velvet worms' jaws are "no more than legs modified for chewing," according to the scientists
Think how weird this is. The shape of the Hallucigenia claw turned out to be pretty handy for chewing, so after a few hundred million years -- voila! -- there's the foot, right in somebody's mouth, chewing. Just goes to show you that evolution is willing to make use of any tool for any job. (But don't try feeding your foot a sandwich. It probably won't work.)
2. Water bears
Way kooler than any Kardashian.
If you don't know about water bears, hang on to your hat. These tiny eight-legged dudes can survive basically anything. No really, anything. Temperatures from nearly absolute zero to above boiling. Enough direct radiation to kill a person. They can dehydrate and go dormant for ten years, and then come back to life, all fine and ready to party. Best of all, they have survived the vacuum of space. All true; look it up and fall in love.
As a longtime fan of both Hallucigenia and water bears, I am so happy to find out they are cousins. How did I miss the family resemblance?
This excellent family tree also includes several fan favorites in the extinct category, such as Anomalocaris and Opabinia. Check your Giant Evolution Timelines for those little guys.

Like the Kardashians, everyone in this family tree is bizarre, attention-getting, and related in confusing ways. They are physically repulsive and riveting at the same time. I can't look away. When's the family reunion? 

Smith MR, Ortega-Hernández J. Hallucigenia's onychophoran-like claws and the case for Tactopoda. Nature. 2014 Aug 17. doi: 10.1038/nature13576. [Epub ahead of print] PubMed PMID: 25132546.


  1. My 16 y/o taught me about water bears last year and loves them! :) I'm passing this on to her.