Join for FREE
It only takes a minute!
Zeiss - Always on the lookout for something special – Shop now

Welcome to BirdForum.
BirdForum is the net's largest birding community, dedicated to wild birds and birding, and is absolutely FREE! You are most welcome to register for an account, which allows you to take part in lively discussions in the forum, post your pictures in the gallery and more.

Sexual dimorphism in birds (...and dinosaurs?)

Reply
 
Thread Tools Rate Thread
Old Sunday 8th April 2018, 18:21   #1
tenex
Registered User
 
tenex's Avatar

 
Join Date: Nov 2015
Location: Colorado
Posts: 298
Sexual dimorphism in birds (...and dinosaurs?)

Sexual dimorphism is so common in birds, I'm starting to wonder whether it all developed after the demise of dinosaurs. Depictions of them have begun to include colors, even feathers, but I don't think I've seen any that suggest dimorphism. Has anyone heard any speculation about this?
tenex is offline  
Reply With Quote
Old Wednesday 11th April 2018, 20:27   #2
nartreb
Speak softly and carry a long lens
 
nartreb's Avatar

 
Join Date: Jan 2013
Location: United States
Posts: 1,185
Good question. I'd say it's not settled.

There have been a number of studies showing individual variations, for example in the crest size of protocerans, which look like they could be due to sexual dimorphism. But there's a shortage of evidence confirming the gender of fossils. Unless you find eggs inside the oviduct, or osteoporosis (calcium deficiency from laying lots of eggs), you can't know whether the dinosaur with a small crest really is female or not, which means it's really hard to tell the difference between sexual dimorphism and (non-sex-related) individual variation.

Last I heard, the statistics don't support any conclusion.

https://doi.org/10.1017/pab.2016.51

That paper may draw an interesting response in the next few weeks, so stay tuned.
__________________
My bird photos
nartreb is offline  
Reply With Quote
Old Wednesday 11th April 2018, 21:08   #3
fugl
Registered User
BF Supporter 2018

 
Join Date: Feb 2003
Location: Reno, Nevada
Posts: 14,263
Quote:
Originally Posted by nartreb View Post
Good question. I'd say it's not settled.

There have been a number of studies showing individual variations, for example in the crest size of protocerans, which look like they could be due to sexual dimorphism. But there's a shortage of evidence confirming the gender of fossils. Unless you find eggs inside the oviduct, or osteoporosis (calcium deficiency from laying lots of eggs), you can't know whether the dinosaur with a small crest really is female or not, which means it's really hard to tell the difference between sexual dimorphism and (non-sex-related) individual variation.

Last I heard, the statistics don't support any conclusion.

https://doi.org/10.1017/pab.2016.51

That paper may draw an interesting response in the next few weeks, so stay tuned.
Thanks for the link.

But dinosaur gender?? Surely you’re not suggesting that dinosaurian sex ID was “socially constructed”? [Beating a dead horse here, I know, but I can’t help it.].
__________________
Bird photos (Flickr): http://www.flickr.com/photos/fugl/
". . .Let them be left, O let them be left, wildness and wet;
Long live the weeds and the wilderness yet."

--Gerard Manley Hopkins

Last edited by fugl : Wednesday 11th April 2018 at 21:11.
fugl is online now  
Reply With Quote

BF Supporter 2011 2012 2013 2014 2015 2016 2017 2018 Support BirdForum With A Donation

Old Friday 13th April 2018, 16:32   #4
tenex
Registered User
 
tenex's Avatar

 
Join Date: Nov 2015
Location: Colorado
Posts: 298
Quote:
Originally Posted by nartreb View Post
Last I heard, the statistics don't support any conclusion.

https://doi.org/10.1017/pab.2016.51

That paper may draw an interesting response in the next few weeks, so stay tuned.
It seems one has to be a subscriber to read that. The statistics sound pretty technical anyway, but I get the point of the abstract. I'm not surprised it's hard to find evidence. Is the "phylogenetic inference" referred to here the argument I began with, from birds?
tenex is offline  
Reply With Quote
Old Friday 13th April 2018, 16:54   #5
fugl
Registered User
BF Supporter 2018

 
Join Date: Feb 2003
Location: Reno, Nevada
Posts: 14,263
Quote:
Originally Posted by tenex View Post
Is the "phylogenetic inference" referred to here the argument I began with, from birds?
Yes, must be, and a weak reed, unfortunately. What’s the earliest evidence for sexual plumage dimorphism in birds, I wonder?
__________________
Bird photos (Flickr): http://www.flickr.com/photos/fugl/
". . .Let them be left, O let them be left, wildness and wet;
Long live the weeds and the wilderness yet."

--Gerard Manley Hopkins

Last edited by fugl : Friday 13th April 2018 at 18:05.
fugl is online now  
Reply With Quote

BF Supporter 2011 2012 2013 2014 2015 2016 2017 2018 Support BirdForum With A Donation

Old Friday 13th April 2018, 21:33   #6
tenex
Registered User
 
tenex's Avatar

 
Join Date: Nov 2015
Location: Colorado
Posts: 298
Quote:
Originally Posted by fugl View Post
Surely you’re not suggesting that dinosaurian sex ID was “socially constructed”?
Yes, they became so preoccupied with that (and similar stuff) that they couldn't see the meteor coming. No lessons there...
tenex is offline  
Reply With Quote
Old Friday 13th April 2018, 22:04   #7
jurek
Registered User
 
jurek's Avatar

 
Join Date: Aug 2003
Location: Switzerland/Poland
Posts: 3,841
Quote:
Originally Posted by tenex View Post
Sexual dimorphism is so common in birds, I'm starting to wonder whether it all developed after the demise of dinosaurs.
See e.g.
https://blogs.scientificamerican.com...-in-dinosaurs/
https://blogs.scientificamerican.com...nd-pterosaurs/

Quote:
Originally Posted by fugl View Post
What’s the earliest evidence for sexual plumage dimorphism in birds, I wonder?
Well known example is Confuciusornis from Cretaceous, but there might be earlier ones.
jurek is offline  
Reply With Quote
Old Sunday 15th April 2018, 15:36   #8
tenex
Registered User
 
tenex's Avatar

 
Join Date: Nov 2015
Location: Colorado
Posts: 298
Thanks, nice articles. It's good to be reminded that sexual selection doesn't require dimorphism, and consider what the likely inferences might be for behavior (care of young). I was listening to the birds this morning and wondering what a forest full of dinosaurs might have sounded like...
tenex is offline  
Reply With Quote
Advertisement
Reply


Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Sexual dimorphism dbooksta Bird Taxonomy and Nomenclature 12 Tuesday 24th May 2016 07:05
Sexual size dimorphism Richard Klim Bird Taxonomy and Nomenclature 1 Friday 15th January 2016 12:50
Birds and dinosaurs Richard Klim Bird Paleontology 3 Friday 14th February 2014 08:31
A question about sexual dimorphism Leiothrix Information Wanted 7 Thursday 20th May 2010 17:21
Dinosaurs and birds OwlTalon Birds & Birding 1 Tuesday 7th November 2006 12:20

{googleads}

Fatbirder's Top 1000 Birding Websites

Help support BirdForum

Page generated in 0.17027998 seconds with 20 queries
All times are GMT. The time now is 16:19.