Author Archives: Greg

Feathered dinosaurs may have changed coats

Some of the most exciting finds of the last couple of decades were the discovery of feathered dinosaurs. These fossils mostly have come from fine-grained formations of the Cretaceous Period in China, where feather impressions were preserved along with the bones. Each of these fossils gives us a snapshot image of the body covering sported by that species. Other recent finds have even given us clues to the coloration of the feathers in a few species.

In yet another new find, announced in the April 29 issue of Nature, we learn that the feathery covering may have fundimentally changed over the lifetime of individuals of at least one species. Two small oviraptors in the genus Similicaudipteryx were preserved at different stages of their life history, each showing the pattern of feathers covering the body at different life stages.

Artist reconstruction of a juvenile and adult Similicaudipteryx. Artwork by Xing Lida and Song Qijin

The smaller, juvenile individual had short flight feathers with a “ribbon-like” stem on its forearms, much long feathers on the tail, and a downy covering over the rest of its body. The larger, young adult individual showed a different pattern, with much longer, and more developed flight feathers with a strong central shaft on the forearm. Thus, the flight feathers of the forearm show two very different morphologies at the two life stages. This does not happen in modern birds, where the flight feathers that emerge on the juveniles are the same, only smaller versions of the adult feathers.

There is some debate that this interpretation of the fossils is correct. It could be, argue some paleontologists, that the smaller individual was preserved during a molting phase, with the new feathers only partially emerged from the tube-like sheath that feathers form in. In other words, they suggest that the different morphology is only temporary and an artifact of preservation. The authors of the original paper maintain it is not an artifact based upon the proportions of the feathers. So, we need to keep digging.

It is now accepted that the ancestors of birds were the theropod (meat-eating) dinosaurs. It is clear from these fossils, and many similar ones, that birds inherited their feathers from dinosaurs, and we have greatly expanded our knowledge of feather evolution with the last few years.

Other dinosaur related posts can be found here. Just search or select the category.

Denning behavior in the Giant Short-faced Bear

One of the most exciting things in paleontology to me is when we can begin to tease apart how extinct animals, animals that humans often never set eyes upon, lived their everyday lives. I am often amazed at how my colleagues can drill deep into questions that at first seem unanswerable; using creative ways to get answers from all the evidence that has survived, the bones, teeth, and sometimes trace fossils.

There are many examples of using the clues provided in the fossil record to come to better understand beasts from the past. In an earlier story, we looked at a disease process in Tyrannosaurus, and glimpsed how the mighty tyrant king could be brought down by a lowly protozoan. Here, we will explore some evidence for denning in the Giant Short-faced Bear (GSFB).

In a paper from several years ago Schubert and Kaufmann (2003) discussed the discovery of a GSFB in an Ozark cave. While incomplete, it is still one of the most complete specimens of the bear ever found. In addition to bones in partial articulation, they also found a thin layer of clay and minerals underneath the skeleton that preserves the remains of hair. Unfortunately, the hair is too deteriorated to tell us what color it was or exactly what its texture might have been, but its discovery is tantalizing.

This Ozark specimen is small compared to others of its species. There is a lot of evidence that there was a significant difference in size between male and female GSFBs. For example, at Rancho La Brea in southern California, both smaller and larger individuals have been found in contemporaneous deposits. It is easy to tell if the individuals are adult, so seeing large and small forms suggests two options: either there are two species, or there is one species with large and small individuals. It later is most likely. This is not surprising as all modern bears are sexually dimorphic.

Schubert and Kaufmann noted that over 1/3 of the known specimens of the GSFB come from caves, and that those specimens are smaller in general than the specimens found in open environments. (See the story about the type specimen, also found in a cave in northern California). It is logical to reason that the smaller individuals using the caves are predominately female.

Modern female bears are much more prone than males to den during periods of unfavorable conditions. And male bears are more likely to remain active throughout the year. It seems as if the GSFB followed a similar pattern—the females were using caves as denning sites, and were denning when they perished. In Cope’s original paper (1879), he called this new animal the cave bear of California—seems he was right.

From the accumulation of small bits of information we continuously piece together the lives of prehistoric beasts, slowly bringing them into sharper focus. That is the thrill of paleontology.

Cope, E. D. 1879. The cave bear of California. American Naturalist 13:791.
Schubert, B. W., and J. E. Kaufmann. 2003. A partial short-faced bear skeleton from an Ozark cave with comments on the paleobiology of the species. Journal of Cave and Karst Studies 65(2):101-110.

There are many other interesting facts here at Boneblogger. Just look around and enjoy.

Nature wallpaper

As expressed in an earlier guest post, having the ability to change out your computer’s wallpaper is a way to express yourself, and to maybe have a window to another world while you are stuck being a desk jockey.

There are many sites to find quality nature wallpaper images for your computer, especially some fantastic pictures of animals, so I thought I would visit many and see what I liked, and what I did not like, about the different sites out there. This is far from a comprehensive list, but is an overview of several, and I did find significant differences between them.

For me, the best sites for nature wallpaper need to have (or not have) several things. First, the site needs to offer good quality images. This is generally something that they all do as there are many great nature photographers out there. However, it is not always clear where the sites get their images that they offer to you.

In addition to good images, there should be diversity. Does the site live up to its promise of offering diversity in the images? For example, at least one of the sites I looked at had long lists of categories of images, with several categories having no pictures. No doubt a work in progress, but if they don’t have the images, maybe they are ahead of themselves in having the category posted.

Finally, are they luring me to their site with the promise of great images only to bombard me with tons of ads and pop-ups? I really hate that and will never suggest a site to you if they look “spamy.”

Using these general guidelines, I created a subjective rating scale of 1-5, with five being the best quality sites, and 1 being the worst (sites with a 0 triggered my McAfee warning, and so are worse than not-recommended). Here are the sites and my rankings (in no particular order):

National Geographic
http://ngm.nationalgeographic.com/wallpaper/download
Overall rating: 5
How can you do better than the photography at National Geographic? Amazing photographs made available to you without a lot of outside ads. You do get lots of NG ads, but that is understandable. In addition to photographs from the magazines, users can upload and share their photos too. You can create an account and collect images that you like. A great photographic resource.

Flickr.com/explore/
Overall rating: 5
Flickr (by Yahoo) is a photography-lover’s site where people can post and share their images. This site is a goldmine if you are looking for great, high quality, and diverse images for your desktop. Because it contains images of people who just love photographs, there are no annoying ads to wade through. However, many of the images are for sale, and you should respect the copyright policies that are listed there. But for getting unusual images for free to spice up your desktop and workspace, this site and Picasa web, get the highest rating.

Picasaweb.google.com
Overall rating: 5
Picasa web is Google’s version of photography sharing, and all of the same can be said for it as was said for Flickr–great images available to you for free for your enjoyment. The same caveats apply, respect the copyright wishes of the photographers and do not use for commercial purposes without permission. But both sites have fantastic images, with more added all the time.

Naturewallpaper.net
Overall rating: 3
This site would have rated higher except for the annoying pop-up ad when you first enter, and the flashing ads throughout. If you can ignore them, some of the images here are very good. They offer images in different resolutions for different sized monitors, which is nice. If you look hard enough (around the big banner ad at the top) you can find links to see the highest rated images and most popular, but you do have to navigate around ads.

http://www.free-naturewallpaper.com/
Overall rating: 4
This site came to myattention based upon a comment below, and I am glad it did. This is a good quality site for images. The image quality is variable, but there are many categories well defined and organized, and while there are ads on the site, they are not too distracting. I note that they also have a donate button, and given that we all need to make a bit to cover the daily coffee bill, I would rather give a small donation that way than have more ads. So, by all means, if you take a little, leave a little.

naturewallpaper.eu
Overall rating: 3
About 13 broad categories of images. The site is clean without too many ads, however some of the linked sites are a bit more spamy, so you might avoid them. I really like that they offer images in different resolutions for different sized monitors. Images nice quality, but not a huge number available.

http://freewallpapers.to/
Overall rating: 3
Another clean-looking site. This site has fewer categories overall, but more diversity. For example, this site has space images, fine art, and digital art. However, their overall collection of nature-themed images is not huge. And, the images are broken into “animal wallpapers” and “nature wallpapers,” so it is a bit harder to navigate I think.

thewallpapers.org/nature/index.php
Overall rating: 1
This site crashed my browser several times. There are multiple pop-up ads. It is not always clear when you click on something in the site that you are going to get re-directed to another site. In short, stay away.

natureondesktop.com
Overall rating: 2
Nice images, but navigation in the site is difficult. Could not find easy categories for sorting of images.

natureswallpaper.blogspot.com
Overall rating: 4
This site has more of a “home-grown” feel, like the person putting up the images shot most of them personally. While they are all nice, many do not have that “professional” look, which is actually nice. There are just a few categories of images listed across the top of the home page. Spending a bit of time digging through the site will likely result in finding some treasures. I personally found the number of flashing ads and scrolling images when you first open the site a bit annoying, and it almost cost the site a rating point from me (that will teach ‘em).

animalwallpaper.info
Overall rating: 4
Nice clean site with quality images of wildlife. Many categories listed, but there are often few, or even no, images in each one. For example, there is one image in the “Gerenuk” category (I had to look that up, it is a species of antelope found in East Africa).But there are no images in the Beetles category, a subject that several of the other sites cover well. The site gets a rating of 4 for ease of navigation, but almost got a 3 for such problems.

jeffreymunro.com/amazingpics/main.php
Overall rating: 5
The author of this site states that he was tired of visitng wallpaper sites and being bombarded by ads (amen), so he created this site. It is clean and ad-free which is refreshing. There are several main categories of images, with the dominate style being landscapes. I found few images of animals, and those were underwater shots. Some very nice pictures and a great place for landscapes.

Elitesavers.com
Overall rating: 0
This site triggered my McAfee warning. Avoid.

So, there you have it. Hope this is useful to you.

Saving Boo boo the chicken

And now, for something completely different.

This video went around on the web a few years ago, and in honor of my friend who is starting to raise chickens, I present it here for you. Enjoy.

Lactococcus is here to stay!

There was a great story recently on National Public Radio about the Wisconsin state legislature passing a bill to name the first state microbe: Lactococcus lactis.

States commonly have a state flower, animal, bird, song, even a state dance, but this is thought to be the first time that a state has named an official microbe.

Lactococcus are cocci bacterium, which means that the individual bacterial cells have a circular shape. Cocci bacteria species can be solitary or they can cluster together. If they group, they can form chains like little pearl necklaces or bunches like grapes. Lactococcus groups in pairs and short chains.

This bacterium has been important in human culture because it thrives on milk sugars (lactose), using the sugar as energy and producing a waste product of lactic acid. Normally this might be a bad thing, but some prehistoric culinary genius discovered that not all was lost if her milk was spoiled by this bug.

By producing lactic acid as part of its digestive activities, the pH of the milk was lowered (becoming more acidic) which causes the milk proteins to curdle, or clump together, thus separating the curd from the whey (the part of the milk that stays liquid). A similar result can be obtained by adding other acids to the milk, such as stomach acid, and it may be that the first curdling was done when milk was stored in a bag made of an animal stomach.

However it happens, separating the solids out of the milk is almost always the first step in the production of cheese. From this step different ingredients are added to make the wide variety of cheeses that we enjoy today.

So it makes since that the Wisconsin legislature recognized the importance of this little “bug” to their state’s economy. In fact, as pointed out by Elio Schaechter of the microbe blog Small Things Considered, we could live without the state animals, but we really could not live our lives without the microbes.

NPR invites people to auggest other appropriate state microbes. You can put your vote in at NPR (include microbe in the subject line of your email). Leave your vote here too. Which microbe is most important to your region?

Boneblogger: Science and the outdoors

Exploring the natural world