John, that video is a fake - it's a viral video advertising sunglasses and the colour change was added digitally in post-production: http://www.snopes.com/photos/advertisem … meleon.asp

(posted in General Biology)

Hi Ken,

this looks like the diaphysis (midshaft) of the tibia of a subadult pig that has lost the epiphyses (end bits), although without the articular surfaces it's hard to be 100% sure.

Hi Lucija,

I don't think that the chameleons make a conscious decision about what colour to chage to in order to match their surroundings. What I think happens is that the passive state (i.e. when not displaying aggressively or displaying to a mate) is fairly drab and will change according to the thermoregulatory needs of the animal.

So if the chameleon is in direct sunlight it will become a lighter colour to reflect more heat, and when in the shade it will become darker to absorb more heat. It just so happens that this means it will also be changing colour to better blend into that surroundings.

I'm no expert on chameleons though, so I'd love to hear if any of the other biologists on the site know more about chameleon colour change or has a different explanation.

(posted in General Biology)

Are you sure this is actually bone? More images from different angles would help.

(posted in Fossils)

It's quite hard to tell from the photos provided. Another couple of angles would help. It may be a fragment of whale auditory bulla, but it's hard to say with any confidence...

Hi Veena,

this looks like the centrum of a whale caudal vertebra (it's too big to be from a dolphin), but I'm afraid it's missing the key diagnostic features needed to identify the species. Certainly a medium to large species.

(posted in Mammals)

Dear Veena,

I don't think this is mammalian bone and it lacks the processes I'd expect from a mandible.

The rugose margins make me think that this piece of bone normally butts against other similar sections of bone to form a bigger structure. The most likely source to my mind would be the plastron (epiplastron?) or carapace (supracaudals?) of a marine turtle, but I'm not aware of any that have such a strongly defined chevron shaped section with such strong fusion along the midline.

If I can find a more definite match I will add a new comment below.

These are fused vertebrae from a marine mammal (base on the apparent bone density), but I'm finding it hard to track down exactly what these are from.

My best guess is that these are from one of the small whales, either the last thoracic and first two lumbar or the last cervical and first two thoracic, although I can't find any good enough comparative images or specimens to make a certain identification... at least for now.

Hi David,

humans evolved from an ancestor that was within the Catarrhine clade, so yes, we evolved from something that was a monkey.

Hi Jessica,

perhaps you could post again saying where in the world you found it letting us know how big it is?

It looks like a sacrum, but it'll be a lot of work to narrow down what it's probably from without a bit more information.

The last common ancestor for these groups would have lived between 113 and 71.2 million years ago, so they have been getting less closely related ever since. If you are interested in how groups are related I suggest taking a look at Date A Clade, which show relationships between major animal groups and if you click on the nodes that connect groups it provides you with detailed information about the evidence supporting that date of divergence: http://www.fossilrecord.net/dateaclade/

Hi Alex,

Before we can consider your question we need to ask "are lungs homologous or analagous"?

Homologies are characters that are shared due to common ancestry.

Analogues are characters that are shared due to common functionality.

As it turns out, the lungs of vertebrates and molluscs (and spiders, etc.) share a common function, but there is nothing to suggest that they are shared in any common ancestor of the various lung-bearing organisms. Their very different structure and development is a good indicator that this is the case.

Therefore, lungs are analagous structures and they can't provide any useful information about the relationships in question.

Hi Paul,

a scale bar would be very useful. Are you sure this is a bird bone? It looks more like the broken ulna of a canid to me.

Hi Teddy,

this is the rib and a portion of carapace of a marine turtle, most likely a Loggerhead given the location and the proportion of the rib extending beyond the margin of the bone of the carapace, although it could be Green Turtle or perhaps a Kemp's Ridley.

Hi Kaija,

It's certainly from a fish, possibly one of the Gadiformes (Cods and allies). Someone else with more fish identification experience may have a better idea about the family and perhaps even species.

(posted in Mammals)

I would agree that they're digits, but I don't think they're pig. I'm also not sure that the round bit is a patella.

It's very hard to be sure from one photograph, but the size, shape and location make me wonder if these could be bones from the flipper of a Manatee. The rounded one looks like one of the larger wrist bones and the other two look like digits. See this image for comparison: http://i461.photobucket.com/albums/qq33 … rP1090.jpg

(posted in Evolution)

I could go into a lot of detail on this, especially about the mermaids, as it's something I've been researching for several years now. However, the main point I will make is that until something has been properly described based on a properly preserved specimen, it doesn't exist as a species (at least in terms of science).

This is important, because stories of dragons and mermaids are far older in origin than this system of understanding species, so what a mermaid or dragon looks like can never be tied down in a hard and fast way - it will change depending on the culture the stories come from and even from variations in the telling.

As it is there are lots of species that have been described that allude to the animal being a mermaid or dragon - there's Draco volans the flying lizard (Draco means Dragon in Latin) or the Komodo Dragon, there are the Sirenia (Sea-cows and Manatees) and Sirenidae (aquatic Salamanders that lack back legs) named after stories of sirens who were mermaids that lured sailors to their death on rocks (orignally not mermaids, but the stories changed over time as I mentioned earlier).

This means that there ARE mermaids and dragons that are known, but they don't really match the stories - however, the stories are all different in many details, so there is no way of finding an animal that would be dragon or mermaid that would meet all the criteria described.

I hope that makes sense!

(posted in Fossils)

Hi Cale, my first impression is that this is a sedimentary feature like a mudcrack, or post burial mineral veins. They can look a bit like fossils if a few intersect.

It's a good question Corwin.

My assumption is that the process (I think it's actually the paramastoid process rather than the styloid, given the position) plays a role in stabilising the head during sustained jumping, which may be why they are more pronounced in some species than others (they seem bigger in the more active jumpers like Red Kangaroos http://museumvictoria.com.au/bioinforma … fuside.htm than in species like the Brush-tailed Rock-wallaby http://museumvictoria.com.au/bioinforma … clside.htm that uses jumping to manouver around a rocky environment).

This is speculation on my part, but you see a similar process in pigs, presumably relating to need to stabilise the head against the forces generated during their rooting action.

Actually, there is a degree of differentiation between skull shapes from different populations. You need a lot of carefully made measurements and you need to compare the data against a large dataset (such as CRANID: http://osteoware.si.edu/forum/osteoware … -wright-0) and you also need to accept the results with a degree of uncertainty, but you can do it at a gross level.

(posted in General Biology)

While Dave is right about this being the rear part of a mammal skull, it is definitely not from a rat. The orientation of rodent temporalis muscle means that there is no saggital crest, but the beginings of a crest are seen here.

Without a scale bar it is hard to work out what size it is, which can help with the identification, but the overall shape makes me think of a small-medium sized carnivore, probably a young adult. My best guess would be a cat based on the shape of the nuchal crest at the back and the shape and relative size of the auditory bullae.

(posted in Mammals)

The cheekbone (or zygoma) also has the masseter muscle attached, connecting to the lower jaw, and it plays an important for chewing. It needs to stretch between the upper portion of the skull and the lower jaw in order for that action to work.

(posted in Fossils)

Sorry I missed this one. This isn't from a rodent, it's from a small passerine bird like a sparrow. I'm afraid there aren't enough details preserved and shown to identify the species from the photo.

Hi Ron,

as Dave says, this is the sternum of a bird, but it's from a Cormorant rather than a gull. The short keel and m-shaped bottom part with a faint v-shape between the base of the keel and the long parts of the m-shape at the bottom is very distinctive.

(posted in Mammals)

Hmm, can't be sure from the images, but my best estimate is the 10th or 11th thoracic vertebrae of a pig - not much better than your guess!

(posted in Fossils)

Hi Alejandro,

If you take a look at the NHM website http://www.nhm.ac.uk/nature-online/life … index.html there are links for each of the hominids described, showing the fossils.

Look like a fish, but it's a bit too damaged to identify species.

(posted in Evolution)

The lineage giving rise to humans never lost the clavicle, the divergence time from the groups that did lose the clavicle (or at least have the clavicle reduced) like the ungulates and carnivores is between 61.5 and 71.2 million years ago, when they split from the bat lineage.

(posted in Mammals)

Hi Sari,

this is the pectoral spine of a fish - possibly from a catfish of some sort.

This looks like the pharyngeal tooth plate of a Sheepshead (Aplodinotus grunniens) to me

It's slightly tricky since the jaw is so eroded, but it looks a lot like it's from a sheep.

Unless it was Tabanus sudeticus the largest species of Horse-fly that you get in the UK (and indeed Europe I believe). They have pale yellow bands on the abdomen and their thorax can look quite fuzzy. Much bigger than many other Horse-fly species.

At first glance I thought this might be the hook of a large species of squid, but then I noticed the asymmetry, which led me to think of the pectoral spine of a fish, but the fact that it's hollow has left me thinking that it could be the dactyl of a crab claw - although it would be a crab with very powerful claws judging by the processes.

Hi Jay,

it would help to have an idea of the size and where you found it - for example, was the cave a sea-cave or near water?

The occipital condyles are very far back and most Wallabys and Kangaroos have them a bit more underneath the skull, although I think the Red Kangaroo and Western Grey might conceivably fit the bill (probably the Western Grey more than the Red).

(posted in General Biology)

It's a fish cranium, looks similar to a catfish, but I'm afraid I'm not able to get this to species level - my knowledge of fish skulls isn't good enough. Someone else on the site might be able to give you a more detailed identification.

Hard to be sure from the photo provided and without knowing whereabouts you found it. However, it looks like the atlas vertebra of a carnivorous mammal, most similar to a dog I think, but possibly a seal.

(posted in Mammals)

It could be wild boar, but it's probably pig. Good work on the identification - certainly suid, but looks a bit too recent to be wild boar, I expect it's from a domesticated pig boar from within the last couple of hundred years.

(posted in Evolution)

It's a tricky question, because there are a number of issues with species concepts when comparing modern vs historic organisms.

With fossils we rely on the morphological species concept - mainly how the organism is shaped. With living species we can use the biological species concept, which is based on the inability of different species to breed and produce reproductively viable offspring.

Since a modern organism could never breed with a fossil form you might want to automatically consider them separate species, but from a morphological perspective there may not be any significant difference in the form of the preserved parts of an organism and the same parts in a living species (where a significant difference is a difference greater than you would expect from normal intraspecific variation for that organism). In this case you would probably consider them the same species according to the morphological species concept.

Of course, there may be many differences in aspects of the biology that have not been preserved in a fossil, so all conclusions about relationships have to be considered with that caveat in mind. Hidden differences are also more likely to occur the older a fossil happens to be, since there would be more time for new characteristics to evolve in that lineage, so very old fossils are unlikely to be considered to be of the same species as a modern organism, even if they look very similar.

Hi Stephen,

the 'horns' on a Giraffe are actually called 'ossicones'. They are similar to a deer's antlers in how they grow, but they aren't shed like antlers and they keep a covering of skin and hair.

Okapi also have them, but only the males, which provides a hint for what they are for. Male Giraffes use their ossicones as weapons in fighting, swinging their heads like a mace into the flanks and legs of opponents.

I'm not sure why the females have ossicones, but they may be for defence.

This is a Hoverfly rather than a bee!

I think this is Helophilus pendulus

It's quite difficule to be sure on the basis of a photo of a dried out and scruntched up specimen, but this looks like it is probably a Thornback Ray (Raja clavata).

(posted in Mammals)

Hi Thomas,

these bones are so heavily rolled that they are very hard to give any good identification for because the characteristic bits are missing.

With more photos the bottom bone might be identifiable to wider taxonomic group (looks a bit like whale) but even that would be hard to be sure of without having the specimen to hand.

Sorry about that!

Hi Bashir,

hard to tell from photos of an incomplete and weathered specimen, but this does look a lot like the skull of a Red-necked Wallaby.

The bone that overlaps the teeth is the descending process of the zygoma, which is the attachment for the masseter muscle, which is used in chewing.

(posted in General Biology)

The simple answer is that the sea has abundant food and the ancestors of the seals that used to live on the land evolved to be better divers while exploiting that food source.

The sort of adaptations we see in seals include large volumes of blood - nearly twice the amount you'd get in a land dwelling mammal of the same size. Blood can store oxygen as a dissolved gas and in haemoglobin, which seals have a lot of. Seals also have a lot of myoglobin that stores oxygen in their muscle. They have large lungs too, but these are mainly for supplying the blood with oxygen before a dive, as they breathe out before going under the water - this helps reduce their buoyancy - otherwise they would waste a lot of energy (and oxygen) constantly fighting against floating.

If you have difficulty imagining how a land living animal ended up living in the sea for most of the time, take a look at otters. Sea Otters are at sea for most of the time as well and they are better adapted for that life than the various species of river otters, but they are still clearly otters. River otters hunt in the water most of the time, but are similar to Mink in their overall appearance (except for being bigger, having webbed feet, flattened tail and some internal physiological differences). Mink also swim and hunt in water sometimes, but they also spend more time on land, so they are less well adapted to the water. Polecats don't really hunt in water, but they are a lot like Mink. Each of these musteilds are very similar, but it's easy to see the adaptations each has to allow exploitation of a watery habitat.

Hi Michelle,

I think this may be a myxogastria slime mould and the little cups on it are fruiting bodies. This group is very morphologically confusing as they can have a wide variety of appearances depending on their phase, and there are hundreds of different species, so I'm not even going to begin to take a guess at what kind it might be!

(posted in Mammals)

Hi Jessi,

although this does look quite a lot like a Common Spotted Cuscus, the shape of the nasal passages where they emerge on the palate is more similar to the Common Brushtail Possum (they are short and quite rounded instead longer and rectangular), which is a species that should be present in the Holgate area.

Good identification skills though - the two species have very similar skulls!

Sounds like one of the many species of Hoverfly.

Hi Tushar,

From my understanding it isn't the different amounts of activation of the individual cone cells, it's the interaction between signals from all cone cells that provide colour information and the interaction between all cones and rods to provide shade information. Therefore colour perception is an emergent property of the complex interaction between lots of simple signals. Does that make sense?

Hi Rebecka,

It's a bit hard to tell from these photos- tortoises can be difficult to distinguish on the basis of the carapace, especially if the image is taken at an angle. It is also really hard to get a sense of scale. However, it was useful to know the size of one of them and knowing where you saw them helps narrow down the possibilities considerably.

My best guestimate would be that if the top specimen is 10cm or less then it could be a Southern Speckled Padloper (Homopus signatus cafer). The bottom one is even harder to be sure of - too big for a Padloper and the angle makes it hard to be sure of the carapace shape, but I think it may be one of the Hingeback tortoises, perhaps a young Bell's Hingeback Tortoise Kinixys belliana.

Hi Rebecka,

The mandible looks like either Sheep, Goat or Duiker - unfortunately the most useful bits to help distinguish between them have been broken off.

The vertebra is a bit more difficult. The size and shape is about right for the 9th thoracic vertebra of a Cape Porcupine, but I'm afraid I can't be certain of that without having the specimen in hand for comparison.