Dinosaurs on the beach

The Ilha de Cajual, in the north of Brazil, is today a tranquil, restful, place. 95 million years ago it was a little more, shall we say, lively, with pterosaurs, giant turtles, and a 14 meter long, 7 tonne crocodile running towards you on it's hind legs!

Just recently researchers at the Universidade Federal do Rio de Janeiro have been displaying fossils of Oxalaia quilombensis, the largest animal of it's type ever found in Brazil. Actually, it wasn't really a crocodile, but a spinosaurid, a type of reptile with a huge crocodile like head that could walk on it's hind legs with a distinctive "sail" on it's back.


So what was life like for Sr. Oxalaia? Well, like most spinosaurids he probably spent most of his time in water - believe it or you can tell this by oxygen isotope analysis of their bones. His skull is characteristic of a predator of fish and small animals, not large prey, and in fact most Spinosaurids tend to be found with fish fossils The need for lots of small meals suggests he was probably quite an active hunter. The sail is a bit of a mystery though, some people say it helped spinosaurids control their temperature, some say it was for display, like a peacocks tail. Could be both of course.

A typical spinosaurid skull

Why "Oxalaia quilombensis"? Well, quilombensis refers to the quilombo, a group of runaway African slaves who were once established on the Isha de Cajual. And Oxalaia is named after Oxalá , one of the highest gods of the Yoruba religion, which started in Africa and spread to the Americas. This African motif is actually very appropriate as the spinosaurids originated there - north Africa and Brazil have so many reptile and fresh water fish fossils in common from this period that there must once have been a land bridge between the two. Oxalaia had plenty of cousins in Africa.

If you would like to know more, Oxalaia quilombensis is properly described in...

Kellner, Alexander W.A.; Sergio A.K. Azevedeo, Elaine B. Machado, Luciana B. Carvalho and Deise D.R. Henriques (2011). "A new dinosaur (Theropoda, Spinosauridae) from the Cretaceous (Cenomanian) Alcântara Formation, Cajual Island, Brazil". Anais da Academia Brasileira de Ciências 83 (1): 99-108.

Darwin's Carnival

It's Carnival time in Brazil. Thousands of people have been working all year on wonderful costumes and floats for this moment, and so it is especially gratifying for this blog that one of the winners, Uniao de Ilha, chose as their theme the English biologist Charles Darwin.

Darwin and his manuscripts

Although most people know of Darwin's voyage to the Galapgos on HMS Beagle, not many know that he stopped off on the way in Brazil. Fortunately, a friend has been kind enough to give me a copy of his diaries.
"It was impossible to wish for anything more delightful than thus to spend some weeks in so magnificent a country. In England any person fond of natural history enjoys in his walks a great advantage, by always having something to attract his attention; but in these fertile climates, teeming with life, the attractions are so numerous, that he is scarcely able to walk at all." he wrote in his journal.


After a quick stop at the volcanic island of Fernando de Noronha the Beagle next made landfall at Salvador in Bahia, where Darwin took the opportunity to explore inland.
"The day has passed delightfully. Delight itself, however, is a weak term to express the feelings of a naturalist who, for the first time, has wandered by himself in a Brazilian forest. The elegance of the grasses, the novelty of the parasitical plants, the beauty of the flowers, the glossy green of the foliage, but above all the general luxuriance of the vegetation, filled me with admiration. A most paradoxical mixture of sound and silence pervades the shady parts of the wood. The noise from the insects is so loud, that it may be heard even in a vessel anchored several hundred yards from the shore; yet within the recesses of the forest a universal silence appears to reign."


Next stop was Rio. Here an Englishman, Patrick Lennon, offered to take Darwin on a trek inland...
"Leaving the coast for a time, we again entered the forest. The trees were very lofty, and remarkable, compared with those of Europe, from the whiteness of their trunks. I see by my note-book, "wonderful and beautiful, flowering parasites," invariably struck me as the most novel object in these grand scenes. Travelling onwards we passed through tracts of pasturage, much injured by the enormous conical ants' nests, which were nearly twelve feet high."

The tree of life

There is material for a 100 blogs in Darwin's journals, which can be found online at
www.literature.org/authors/darwin-charles/the-voyage-of-the-beagle/

For now I will only add a passage from the journey after Rio, down to Montevideo
"In our passage to the Plata, we saw nothing particular, excepting on one day a great shoal of porpoises, many hundreds in number. The whole sea was in places furrowed by them; and a most extraordinary spectacle was presented, as hundreds, proceeding together by jumps, in which their whole bodies were exposed, thus cut the water. When the ship was running nine knots an hour, these animals could cross and recross the bows with the greatest of ease, and then dash away right ahead. As soon as we entered the estuary of the Plata, the weather was very unsettled. One dark night we were surrounded by numerous seals and penguins, which made such strange noises, that the officer on watch reported he could hear the cattle bellowing on shore. On a second night we witnessed a splendid scene of natural fireworks; the mast-head and yard-arm-ends shone with St. Elmo's light; and the form of the vane could almost be traced, as if it had been rubbed with phosphorus. The sea was so highly luminous, that the tracks of the penguins were marked by a fiery wake, and the darkness of the sky was momentarily illuminated by the most vivid lightning."

Jaca

The Jaca (Artocarpus heterophyllus) is one of several fruits well known in Brazil, but unlikely to find itself in a supermarket in England. Actually it's originally from Asia, and is for example, the national fruit of Bangladesh.

The Jaca, or Jack fruit to give it it's English name, holds the distinction of being the largest fruit in the world, reaching an incredible 36 kg in weight! Because of this the fruit are not out on the branches, which would break under the stress, but hang directly from the trunk. The trees themselves are large and stately reaching up to 25m high.

As I said, the Jaca originates in Asia, and was probalby transported to Brazil from Kerala by the Portuguese. But it flourishes in the Mata atlantica, and indeed is sometimes considered a pest! It's fruit are eagerly devoured by coati, which then deposit the seeds around the forest, where the fast growing Jaca (1.5m/yr!) often out strips native species. This also artificially boosts numbers of coati who then go on to raid nests for eggs and nestlings. Because of this national parks often clear wild Jaca saplings, with, for example, over 50,000 being culled from the Tijuca Forest park near Rio between 2002 and 2007.

Eating a jackfruit is, problematic. Firstly, mature fruit emit a strong, distinctive smell, said to resemble rotting onions. Secondly, the fruit is covered in spines, thirdly cutting the fruit relesaes a sticky latex which will accumilate on knives and skin unless pre-coated with cooking oil. And fourth, the flesh tastes of banana, which is itself enough to dissuade this author!

Although there seem to be many delicious recipes for Jaca from Asia, I could not find any from Brazil. The fruit is ususually eaten fresh, or as a juice. Take care though, the flesh is hard to digest, and, anecdotally, several people have died from getting carried away and eating a whole one!

Food tips for vultures

An iconic image of the Mata Atlantica is a flock of vultures* circling high in the sky, soaring lazily on thermals as they peer down looking for carrion. That's all very well, but frankly they could be up there all day without seeing anything, especially if the dead meat is under a forest canopy. What a hungry vulture needs is a short cut. There are several.


As I mentioned in a previous blog, some carrion hunters can detect the ethyl mercaptan from rotting bodies and so fly low over the forest until a whiff catches their attention. Black vultures simply use their superb vision to keep track of these birds, follow them in and nick it. There are not many creatures who will stand up to a determined gang of black hissing vultures** with a 5ft wingspan, not least when they use vomit as a defensive manoeuvre.


Black vultures roost together, setting off around sunrise on their daily hunt for corpses. Now, if there was a dead cow around yesterday there is a fair chance that something will still be left today. But maybe not much, and certainly not enough for everybody. It's been shown that Black vultures returning to a meal head off earlier in the morning, flapping energetically to get there beaks in the feeding trough first. Unfortunately, it has also been shown that the smarter vultures know this, and so follow any birds trying to sneak away surreptitiously before dawn, so there is invariably a crowd for breakfast. Still, as it might be you doing the following tomorrow, this seems to be generally accepted without too much rancour.


And lastly, one can just wait for food to drop dead in front of you. A common sight along many highways are vultures perched on the street lights - roads might be a bane for many animals, but they're a boon for vultures. High perches with a clear view are exactly what they need - life is after all a balance between energy spent and energy gained, spend none and you are half way there. Roads are also noisy, chaotic places, which is nothing new to a vulture, but tends to keep larger solitary raptors at bay. And lastly of course a steady diet of road kill, though not as much as you might think. Surveys show about 0.1 to 0.5 mammals per km per month, mostly possums and not enough for a growing vulture. So, unfortunately, the vulture does have to go and search for food the traditional way, but every little helps.

* a "kettle" apparently, though a "kettle of vultures" conjures up all sorts of unpleasant images
** a "venue" - this I can understand

Hello possum

The is the black eared possum (Didelphis aurita), also known as the Gambá-de-orelha-preta or Saruê, a species of opossum found in Brazil, Argentina and Paraguay. A bit bigger than other possums in South America (60 to 90 inches long and up to 1.6 kg), but with a relatively shorter tail as it's not in the trees quite so much. They do climb of courrse, just not so fast or dexterously. On the other hand, on the ground they are faster than other possums and it's been shown they can see quite a lot further.

Photos courtesy of Heliana Soneghet Pacheco

Although possums do look a little like rats, in fact they are marsupials. The mother gives birth after about 13 days to 8 tiny possums which crawl into a pouch and then suckle for about 100 more days. By the end they are quite a weight to carry around! Babies born at the end of one breeding season are able to reproduce at the start of the next , which can lead to a lot of possums. Actually, possums tend to spread out as they are quite territorial, especially the females, with about 0.5 to 1.5ha depending on how good the territory is.


So what do possums eat? Well, pretty much everything. Insects, fruit and lots of small mammals, they have actually been recommended for keeping down levels of mice. Rather more impressively, they also go for snakes! Somehow they manage partial or even complete immunity to the venom of many species including the fer-de-lance, Bothrops asper, whose bite can be fatal to humans.

When they meet something too big to eat, and too fast to run from, they "play possum", ie. play dead. This can be surprisingly convincing, even including a smelly secretion to suggest that they've started to "go off". As many predators prefer live food this is worth a try as a last resort, but it doesn't work terribly well against oncoming traffic. Nonetheless the Saruê is a success story, and has otherwise adapted well to the modern Mata Atlantica.

Feliz Natal / Happy Christmas!!

Why did the sloth cross the road?

A good question, as sloths are not really compatible with motor transport. Nonetheless this one decided to go where no sloths had gone before, and started to cross a busy road in the hills above Vitoria. Ten minutes later he was still there, making painfully slow, but determined, progress with now an audience from the cars and lorries who had stopped to let him pass.

TVGazetta 14 Dec 2010

He, or indeed she, it's hard to tell with sloths, appears to be a Maned sloth (Bradypus torquatus) found especially in the Atlantic forest, from Rio to Bahia and one of six types of sloth in South America. Maned sloths have very little muscle mass for their size, which saves weight when hanging from branches, but it does mean they can hardly stand on the ground, let alone walk. Their only means of locomotion is to slowly drag themselves along (if attacked they stop completely and lash out with their claws, which can be surprisingly effective).


But why exactly are sloths so slow? They are very, very, specialised in what they eat, concentrating on leaves of forest trees, especially Cecropia, a common pioneer related to nettles. This has pros and cons. The pros are that leaves are very abundant and easy to catch, the cons that, well, leaves are rubbish as a food. That's why so few animals eat them. There is very little nutrition or energy there, and what there is is extremely hard to digest. Even sloths, with specialised stomachs full of plant digesting bacteria can take up to a month to digest their food so that as much as two thirds of a sloths body weight can be just it´s stomach contents. With very little energy to spare, sloths save all they can. They have very low metabolic rates, and low body temperatures. Mostly they just hang in trees, using special hooked claws so that even this doesn´t take much effort.

Sloths seem to only leave the tree tops for two reasons. Firstly to defaecate, which they do one a week, usually in the same place. Quite why they do this isn´t exactly clear, though the smell might help to attract a mate, otherwise a bit of a problem for an animal that normally hardly moves. Which brings us to the second reason, and maybe the answer to our question. Why did the sloth cross the road? To find another sloth!