(posted in Mammals)

It was probably a fine swimmer but its lifestyle is thought to have been more of a "lie and wait" predator similar to modern crocodiles. So definitely not as capable as modern whales, but probably not bad either.

(posted in Mammals)

Hi Went,

As far as I know we don't have any soft part preservation for Dimetrodon, so much of what we "know" about the sail is inferred from the structure and anatomy of the neural spines themselves. One species, Dimetorodon giganhomogenes, has neural spines that bend sharply at their terminal end. It's been interpreted that the bending would have prevented the sail from extending all the way up the spines. This might mean that the sail didn't extend all the way up in most species, or it might be that this species was unique. It's not possible to say without more fossils. If you have access, you can read the article about that species here: http://www.bioone.org/doi/abs/10.3158/2 … 20-5.1.104

Hi Evan!

You are correct that crocodilian and birds are both archosaurs, but having hollowing bones is not what defines the group. Archosaurs are defined by having teeth set in sockets (even if birds eventually lost their teeth), certain holes in the skull and jawbones, and a specific ridge on the femur bone. Hollow bones first evolved in Theropoda, the group of meat-eating dinosuars including animals like Tyrannosaurs rex and Velociraptor. Birds are also theropods, and the hollow bones certainly helped them be light enough to evolve the ability to fly. Fortunately crocodiles can't fly, because that would be terrifying.

(posted in Mammals)

Interesting question!

Quick answer: As far I know we don't have any direct evidence for what Dimetrodon's skin was like but it is usually depicted with smooth skin or scales.

Dimetrodon was part of a group of animals called Synapsida, which is distinct from reptiles based on the placement and patterns of holes in the skull. This means that Dimetrodon is part of the group from which mammals eventually evolved, but itself was definitely not mammalian. Some early synapsids are thought to have possessed boney armor embedded in their skin, which may have looked superficially like scales but are not formed in quite the same way. It is unclear when fur first evolved in the fossil record, but the earliest undisputed fossil imprint of hair is from the late middle Jurassic (164 million years ago), which is long after Dimetrodon would have gone extinct in the Early Permian (272 million years ago).

The scientific name for a giraffis is Giraffa camelopardalis. Remeber that when writing scientific names you want to use italics (or unline it if you're writing by hand) and to capitlize the genus, but not the species.

The story I always heard for the species name of giraffes is that the Romans saw the animal as a mix between a camel and leopard, hence camelopardalis.

(posted in Mammals)

This is a great question!

All cats are hypercarnivores, meaning that the majority of their diet has to be meat. Their digestive system is super-simplified, because meat is relatively easy to digest compared to things like plants, especially grasses which have very little nutrients. One of the reasons we think cats all have such similar morphologies (i.e. bodies) is because an all meat lifestyle is so restrictive that they are limited in the ways they can evolve, no matter where they live they have to abide by the same lifestyle: hunting prey and eating meat. Funnily enough, the two "big" cats you mentioned (cougars and cheetahs) are not actually big cats. There are only four big cats: lions, tigers, jaguars, and leopards; all other cats are considere "small" cats regardless of size. I'm not sure why domestic cats will occasionally chomp on grass, but I suspect the reason larger cats don't is because for their digestive system there is zero nutrients to be obtained from consuming things like grass, and to do so would be a waste of time and energy that they could spend hunting. Hope that helps!

What happened to me was I finished a BS in Ecology & Evolutionary Biology while taking some paleontology courses in the Earth & Environmental Sciences department and working in a paleontology lab on campus. I realized that I wasn't happy with just the biology degree, and asked the PI of the lab if he could suggest some additional courses in geology to help me get into grad school if I ended up in a geology or earth sciences department. He had been hoping for a while to put together a joint biology/geology degree and it had never happened, but he was happy to suggest some courses, and I ended up taking enough to get a second BS in Environmental Geology. The lab I was working in focused on stable isotope ecology, so those were the kinds of researchers I looked for when searching for grad schools, and I ended up doing a Masters with someone who had done stable isotopes during their PhD but was transitioning to microwear, so I got a bit of experience with both techniques.

I think the undergrad degrees were great, but I never would have pursued paleontology as a career without that experience in a working lab, getting my hands dirty and seeing what doing the science was really like. Hope that helps!

Looks like conglomerate to me. It's a type of sedimentary rock that forms in relatively high energy environments where the embedded stones called "clasts" are embedded in a finer grained matrix.

Hope that helps!

First off, this is a GREAT question. If you find yourself compelled by these types of mysteries I hope you will consider a career in science, because thinking about these seeming inconsistencies is what we're all about!

To answer the actual question, I must first point out that the premise is flawed. While animals have never evolved the ability to produce chlorphyll and thus utillize phosyntheiss, that doesn't mean that no animal has ever evolved the ability to get energy from photosynthesis. Any animal that eats plants is, in a sense, getting energy from photosyntehsis, and I grant that this is probably not what you meant, it's worth point out all the same. However, there are animals that have figured out how to use photosynthesis to their more direct advantage.

I'm speaking of the sea slug Elysia chlorotica, which captures cholorphyll from it's food and uses those orgenelles to produce food for itself. Studies have also shown that these cholorphyll can be passed down generation to generation. So there are absolutely animals that make use of this metabolic pathway.

However, and this is a big however, photosynthesis is simply not as productive as cellular respiration. If I remembr correctly, photosyntehsis produces 4 adenosine triphospahte (ATP) molecules per cylce, whereas cellular respiration produces around 38 ATP. This is a substantial difference and it shouldnt be hard to see why evoultion might favor a pathway thte produces so much more energy even if it's not at a primary level.

I hope this makes sense and encourages you to explore further. These are the right types of questions to be asking so if you keep at it you'll be a scientist yet!

While it's true that cats and humans probably have been living together for at least 6,000 years, the story is a bit more interesting than just that.

Cats, by and large, are solitary animals, so it is pretty cool that a group of them developed a close association with another species. The thinking is that when agriculture reached a certain point of productivity then there was more than enough food for a season, meaning some could be stored for the next year. The problem was that this also provided a nice meal for vermin, who would eat the grain over the winter. Unless of course there was a cat living in the storehouse to eat them first. Eventually, the cats less stressed out by being around humans would have become domesticated, similarly to what may have happened with wolves into dogs.

Hope that helps!

We actually covered this topic on my podcast but the take home message is that you can't really answer "why" questions with evolution, which David was sort of getting at but didn't say out right.

We, and other primates, are as smart as we needed to be to survive up until this point. So ultimately any answer to a "why" question about evolution can be answered with, "because that's what worked." Not terribly satifisying but if you start thinkin about what pressures drove primates to develop intelligence you might get a more substantial answer.

Sorry for the shameless plug but we go into much more detail in the episode. The segment with our discussion begins around an hour in. Here's the link: http://www.sciencesortof.com/2013/02/ep … d-the-sea/

(posted in Mammals)

I was able to find an older paper covering the morphology of pangolin scales, which might answer some of your microanatomy questions.

http://onlinelibrary.wiley.com/doi/10.1 … x/abstract

And another more recent paper covering some recent molecular work, which talks a lot about the genetics.

http://onlinelibrary.wiley.com/doi/10.1 … 577.x/full

Hope those help!

For awhile it's even been debated if bats should be put into a single group (called a monophlyly) but from what I understand it's been put to rest that all bats do share a single common ancestory.

I've seen a few different options for the sister clade to Chiroptera. The Tree of Life project has them grouped with Dermopterans, commonly known as flying lemurs even though they aren't primates, but supports you notice of some morphological similarities.

An analysis that came out just this year looking at DNA amongst other evidence put bats as the sister groups to Carnivorans, diverging sometime in the late Paleocene. Here's a link to the paper: http://www.sciencemag.org/content/339/6120/662.abstract

As we find more fossils this very well might shift again, science is always progressing!

(posted in Mammals)

I remember seeing at one point that it was thought that mane color was related to the overall health of the male in terms of how often he fed, but the the body was still 'tan' in color, which makes sense given their savannah environment.

I always felt like the biggest innaccuracy, though there are of course many to choose from, is the noise T-rex makes as it approaches. While great for dramatic effect, walking like your legs are two pile drivers is not very efficient, energentically or in terms of hunting prey. Looking at the anatomy, it seems like T-rex would have had a pretty springy ankle and definitely wouldn't have caused mini-earthquakes with each step.

I'm sure others will chime in with their favorites but that's my pick.

And as a side note, gender as a term can refer to things like sex, but it can also connotate a social aspect which isn't really applicable to animals (that we know of). If you're asking specifically at chromosomes and anatomy, it's more clear to just use the word "sex."

And just for fun, there are hermaphrodite slugs that will fight be tearing off each others penises forcing the losing slug to live out the rest of their life as a female!

I believe the simple answer is "no."

One of the leading theories as to the cause of the Permo-Triassic extinction is the release of CO2 from volcanoes in Siberia known as the Siberian Traps. While these eruptions were massive, and sync very well with the timing of the extinction, they occurred over the course of about a million years, so nowhere near as fast current rates of CO2 release by anthropogenic sources.

In regards to the second part of your question, the climate change seen during the Paleo-Eocene Thermal Maximum (PETM) was indeed slower than modern climate change, but at the same time is one of the fastest instances of wamring in earth's history, making it a good study system for looking at envrionmental responses to rapid climate change. The cause of warming during the PETM is still debated, but we know from looking at stable isotope geochemistry that there was an influx of carbon into the atmosphere and ocean coinciding with the warming event. It's possible that this source of carbon was methane (CH4), not CO2, which could have been released from the deep ocean, but again this is all still being researched.

The take home message is that the amount of CO2 being released into the atmosphere since the industrial revolution is indeed much faster than anything earth has experienced before.

(posted in Mammals)

Looks like a maned wolf to me. Reddish color, pointy ears, long legs, relatively short tail.

Except they're only found in South America. Any zoos in the area that might have lost one?

In Spanish speaking countries one common name for puma is Gato monte, which literally means "mountain cat," which could be another source of confusion. This is also where the term "catamount" comes from, which is another colloquial term for pumas.

When an animal has such a wide distribution it's not surprising for it to have regional variations in it's name. I've even heard pumas called "deer tigers" due to their penchant for mule deers in certain parts of their range.

Puma size varies quite a bit across their range. In the tropics (where they overlap with Jaguars) they tend to be smaller, whereas in colder climates like Canada they can get to be quite large and have been know to hunt moose!

However, even if they two that were fighting were the same size they're built a bit differently. Leopards have powerful shoulder muscles for tackling prey, whereas pumas have very large hind limbs and are excellent jumpers. Both animals are ambush hunters but when they can pumas like to drop down on prey from above. While leopards will carry prey into trees I do not believe they hunt from the tree itself.

I think it comes down to environment. In a grassland I might give the edge to the leopard, but if there was enough terrain that the puma could get above the leopard the puma might have better odds. So it kind of depends which variables are being controlled for in the confrontation.

And a jaguar could take them both. ;-)

(posted in Mammals)

Not only do they come down from their trees once a week, they are very systematic about it. They use their short stubby tails to dig a hole at the base on their tree which they then defecate and urinate into. Afterwards they cover the hole back up. This is all presumably done to cover the smell so a passing predator won't notice the smell then investigate the tree further.

This answer also applies to two-toed sloths.

Looks like it could be a seal vertebrae. Looks similar to a harbor seal vertebrae I've seen from the Moneterey Bay area, and harbor seals do also live in the waters around Maine. Size seems about right too.

I'm not an expert on post-cranial skeletal identifcation, but hopefully it's better than nothing.

Here's a link to an image I found that looks very similar: http://img3.etsystatic.com/000/0/549710 … 342595.jpg

(posted in Mammals)

I've done some digging and may have a few answers to add.

You are correct in that top speeds for lions are probably betwee 30-35 for very short distances. However, more modern works still just reference Schaller, as you mentioned.

Beyond that. I couldn't find anything for tigers, leopard, etc. I found one paper that mentioned modern cats, but it's from the 1980's and I couldn't quite make sense of the way the tables are laid out. Hopefully it makes sense to someone else and they can interpret it. Open access pdf found here: http://jeb.biologists.org/content/97/1/1.full.pdf

I too find it odd that so little work seems to have been done on these animals, I guess the nautre of the ambush predator doesn't lead to much interest in top speed.

(posted in Mammals)

I know this is a very old question but I have two points I'd like to add. Neither answer touched up on the "man-eating" aspect. To my knowledge, there is no evidence of Thylacoleo eating humans. The decline of these animals seems to overlap with the arrival of humans to Australia, so it may have even been the other way around (although there is much debate on that topic).

Secondly, in addition to the "marsupial lion" I've also heard this animal referred to as a "giant killer wombat" which is both funnier and more taxonomically accurate nickname.

(posted in Fossils)

Cool question! And believe it or not, not the first time I've answered something like this. I'm no expert on footprints, but I know a thing or two about geology so here's my interpretation.

What you're seeing here are probably load casts. These are features that form before the rock has fully hardened or lithified. They are caused by another layer coming down on top of the still soft substrate and leaving impressions that get preserved as the rock becomes hard. I've posted an image from the side so you can see what I'm talking about.

It's easy enough to imagine how several load casts could look like a footprint when viewed from above, so I think that might be what's happening here.

However, there are many fossil footprints out there, and it's hard to say definitively without knowing where in the world this shale came from and how old it is. My interpretation of it being a particularly foot shaped load cast is because I live in an area with shale that formed over 400 million years ago in the ocean, so there are no footprints to be found even though people claim to find them from time to time.

Leo is the species name for a Lion.

And Owl for O.

(posted in Mammals)

I'd like to expand a little bit from a taxonomic perspective. The term "Marine Mammal"is a little confusing since there are several different orders which have produced aquatic members.

Dolphins and whales form the order Cetacea and their closest living land relatives are artiodactyls like hippos and deer.

Otters are in the order Carnivora, with dogs, cats, bears, and weasels.

Manatees are in the order Sirenia, closest living relatives are things like elephants, and there have been members like the Stellar sea cow which were entirely marine. Manatess themselves have no problem in salt water, but to my knowledge they can't drink salt water to stay hyrdrated. They also have temperature tolerances so they like to stay in warmer shallower water for comfort, protection AND to find food as David said.

So the take home is  take home is manatees do things differently because they evolved along a completely pathway than any other living marine mammal, so no surprise that they do things differently.

For what I understand Lion subspecies taxonomy is still actively debated within the field. I've seen estimates between 2 (Africa and Eurasia) up to 6 or 8 depending on the source. And that just includes modern species, there are a great many fossil specimens that are argued as extinct subspecies of lion, including some in North America. Then there are those that argue that none of the subspecies are distinct enough and they should all be clumped together as a singular species.

You phrased your question as "genetically valid" which I think might lead to some confusion as using genetics is relatively recent and most past estimates (especially fossil taxa) were based on morphology not genetic sequencing.

Sorrry there's not straight answer for this one, biology can be tricky like that!

To my knowledge there is nothing preventing various types of fungus from growing on sloths. I'm not sure where you heard that fungi cannot grow on sloths, but I've read reports where they claim that there was BOTH algae and fungi living on sloth hair. That's not to say you shold expect to see a sloth with mushrooms on their back, because there are many many different types of fungi which are just as tiny as algae (yeast for example).

More generally, the development of mutualisms between plants/fungi and animals  is not an equal opportunity deal, so if there was a species of algae that was able to colonize a sloth first it may just be able to competitvely exclude new arrivals like fungi, but that's just speculation.

(posted in Birds)

The closest living relatives of terror birds are the seriemas, two species of South American birds from the family Cariamidae, which is the only extant family from the order Cariamiformes, of which Phorusrhacidae was also a member.

The largest known Phorusrhacid is the Kelenken guillermoi, which is known only from its skull but may have reached sizes up to 3 meters in height and weights of 230 kg.

A study from 2005 modeled the potential maximum speed of the subfamily Phorusrhacinae to be around 50 km/h.

(posted in Mammals)

Based on a quick glance at the literature and some rough measurements of this image I'd say it's fairly accurate.

The man is ~ 1.75 m, and the animal is about twice his length. The head is a little shorter than the man himself.  And the height at the shoulder is tough to estimate from this drawing but also seems ok.

I don't have the exact measurements for a VW Beetle, so I cannot say if it is to scale with the man or the Daeodon.

For some more ideas on getting into conservation:

I don't know where you are or what level of schooling you're at, but if you have a zoo nearby you could see if they're looking for interns or volunteers. You probably won't get to work with large predators directly, but you'll learn lots and make contacts with people interested in conservation.

There are also study abroad opportunities to go learn about conversation first hand. I did something like this in Costa Rica and we got to visit a big cat sanctuary (no cheetahs, obviously) where they care for injured animals of all kinds. It's a great way to get your feet wet and find out if a career in conservation biology is something you really want to pursue.

For classes, definitely look for a conservation biology course, but also consider comparative zoology or anatomy, animal physiology, or even a conservation or environmental policy course to learn about the political messiness that can accompany conservation efforts in developing parts of the world like Africa.

Good luck and definitely be prepared to work hard!

I'd say that's a suid, aka some type of pig, boar, peccary, etc.

Perhaps someone else can narrow it down to a genus or species, but I will comment that if it's bigger than a bear, it likely wouldn't be a carnivore since bears are the largest land carnivores alive today. 

Marine mammal bones tend to be very dense, and sometimes even smell of fish oil (you are what you eat).

Hope this helps!

In my lab when we're working with bone or enamel we use hydrogen peroxide to remove organic material from the sample. And after that we do rinse it with ethanol, but that really only serves to help it dry more quickly.

It's also possible you were seeing a Gray Fox or Coyote, both their ranges cover Ohio and can have enough patches of auburn/red fur that you might mistake them for Red Fox (which is actually an invasive species from the UK).

I have another idea, obviously a photo would help a lot, but there have been instances of coyotes breeding with domestic dogs aka coydogs. They're not super common but they can look weird, i.e. not really like a dog or a coyote, and I've seen photos of some that are quite stocky.

My other idea, also completely theoretical without a photo, is a black bear suffering from mange. A lot of the hair falls out and the sloping profile of the bear from a distance could look like the sloping profile of a hyena.

Those are my two guesses, hope you see it again and get a snapshot!