Fins to Feet


Evolution of the horse
November 5, 2011, 2:38 am
Filed under: Uncategorized

NOTE: This piece is under construction!

From left to right: Napoleon, Alexander I, tsar of Russia and the poster for Griffith's Birth of a Nation

An armed man on a rearing horse – this is the very image of martial valor. And it’s been done and redone by a great many artists over the centuries. The soft, glowing colors, stately battle gear and upraised armaments do set quite a scene, but the subject in these sorts of compositions – for me at least – has always been the horse itself, with muscles strung taut, nostrils flaring and hooves ready for the charge. Although the age of cavalry charges and horse-drawn plows has long since past, the horse remains a potent cultural and historical icon – more than 40,000 books have been written on the subject, from Xenophon to Michelangelo – and it might be worth investigating how this remarkable animal came to be. Happily, fossil horses are abundant and we can answer many questions about horse prehistory with some measure of certainty.

The horse fossil record is often seized upon by writers of elementary textbooks as a classic example of how paleontology can help inform our understanding of long-term evolution. Horse evolution, in these instances, is usually portrayed as a sort of evolutionary ‘procession’, with the humble Hyracotherium (invariably described as being “about the size of a fox terrier”) shunted off to the rear and the high-shouldered and gallant Equus leading the parade. Long term readers of this blog will know that evolution is a tremendously bushy affair, and that these sorts of neat, linear progressions are simplistic. Nonetheless, it does capture certain important trends we shall discuss in the succeeding paragraphs.

How do horses fit in, taxonomically speaking, with respect to other hoofed animals?

All hoofed mammals fit into the cladistic group, Ungulata. Hooves are, essentially, the modified tips of toes – and differences in the structure of the foot can be used to divvy up the ungulata into two broad categories: even toed ungulates and odd toed ungulates. Animals in the first category sport two major weight-bearing toes – the third and fourth toes of each leg. This group includes camels, goats, cattle, deer, pigs and a number of other hoofed animals. Odd toed ungulates, on the other hand, support themselves, for the most part, on one toe per foot – the third toe. This group includes horses, tapirs and rhinos.

There is evidence to show that, among the ungulata, horses share a more recent common ancestor with tapirs and rhinos. For one, the odd-toed ungulates all have an extended caecum (an outpocketing of the large intestine that is found in greatly reduced form in humans) that helps ferment and digest the cellulose in grass. They also share striking similarities in the anatomy of the teeth and the ankle bones.

Equus is the only surviving genus of the family equidae, and it includes 3 species of asses, 3 species of zebra and the horse.

Hyracotherium to Equus

Hyracotherium is the earliest known fossil horse. This unassuming animal was about 20 centimeters high at the shoulder and was probably a browser, seeking out its fill amidst the leaf-shrubbery rather than out on a grassy plain, as modern horses do. It lived around 50 million years ago, just 15 million years shy of the extinction of the dinosaurs (the Eocene). It spread throughout the Northern Hemisphere and was, by most counts, an evolutionary success story. But it differs from the modern horse in a number of key respects:

1) The modern horse dwarfs the dog-sized Hyracotherium.

2) Hyracotherium has four toes, whereas the horse sports a single sturdy toe/hoof on each foot.

3) the low crowned teeth of Hyracotherium imply a diet of soft leaves. shoots, nuts and fruits. Modern horses, however, are adapted to high-fibre grasses

4) the brain (specifically the frontal cortex) of the modern horse is considerably larger than that of Hyracotherium.

Why did horses get bigger?

Well, for starters, the fossil record does not tell us a story of uniform progression towards larger body size. For example, some of the distant descendants of Hyracotherium, like the Pliocene horse Nannipus, were even smaller than the earliest horses. The body size of Equids remained roughly constant for several million years before large horses appeared on the scene.

So what selective pressures might have led to an increase in body-size over time? The typical explanation has to do with large body size being a line of defense against predators on the open plains. It may also have to do with the shift in diet from high-quality forage to nutrient-poor high-fibre grass (which was roughly concurrent with the spread of open grasslands throughout the world).

In terms of energy derived per unit bulk, horses cannot process food as efficiently as even-toed ungulates that chew their cud and have a modified stomach with four chambers. The fermentation process that digests cellulose (with the aid of symbiotic bacteria) in the caecum of the horse is almost exactly mirrored in the proverbial “four stomachs” of cows and goats. While they cannot match even-toed ungulates for energy efficiency per unit mass, they can push a greater amount of material through their digestive system in a given amount of time. They are also specially adapted to subsisting on low-quality grasses which their even-toed counterparts could not survive on for long.

Larger animals are able to conserve energy better (on account of their greater ability to retain heat compared to smaller animasl) and this might have been driving force towards greater size. Body size may have also contributed to an increase in running speed.

Hooves and legs

As horses became more adapted for life on seas of rolling grass, they underwent a number of crucial anatomical changes. The length of the bones of the foot increased (a trend we saw in earlier posts on cats and theropod dinosaurs) and the number of hooves decreased, with the third digit becoming more pronounced: these are both adaptations for a cursorial lifestyle. The arrangement of tendons in the lower leg and the connections between the leg bones work to store elastic energy and reapply it with each stride (the so-called “springing step”). Horses have even evolved a way to expend less energy standing up than sitting down.

Grasses are hardy plants and have evolved various means of protecting themselves from plant predators. They inflict heavy wear and damage upon the teeth of herbivores. And, as a consequence, herbivores like the horse, have evolved high crowned teeth, covered in cementum with folds of enamel (hypsodonty) to deal with the tough food. Many of premolars changed to molars. There is also a long gap between the incisors and the premolars that is absent in the very earliest horses, like Hyracotherium. This adds distance between the nose and the eyes, allowing the horse to keep an eye out for predators whilst grazing. Rather fortitiously, it also provides space for the insertion of a bit, an important part of horse riding.

The Horse brain also increased in relative size over the course of the last 50 million years, although the precise reasons for this change are uncertain. It may reflect a major increase in intelligence (a notoriously difficult concept to define in animals to begin with) or may be related to the increasing complexity of the sensory apparatus of the horse.

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Little stuff
September 8, 2011, 11:46 pm
Filed under: Uncategorized

So I’ve hoisted up a new banner for the website – let me know if you love it or loathe it. I’m somewhat ambivalent about it myself …

Frankly, I haven’t been good about posting here with anything even approaching regularity, so it’s no wonder that the growth of my “readership” (if it can be called that) has proceeded in fits and starts – jumps punctuated by long periods of declining traffic. I’ve gotten comfortable seeing this history as a long-term project that I can return to whenever the circumstances suit me. But blogging doesn’t work that way and the lengthy pauses in my progress have prevented me from really building up a regular audience. I’m going to to try and reduce the content-to-post ratio to manageable levels, so I can post more often.

At any rate, I really am quite appreciative of those who have taken the time to read my material or even link to it in the past! These include David Orr at Love in the time of Chasmosaurs (I’ve been a long-time reader of his blog!) and David Tana at Superoceras, both fine science writers well-worth checking out.

Also, there appears to be an industrious soul by the name of Henrik Osterman who is about to release a paleontology-centric podcast over the course of the next few days – something I’ve rather been looking forward to! So head to over to palaeocast to get a hold of the program when it gets out.



Jawless Fish
September 5, 2011, 6:19 pm
Filed under: Uncategorized

A whale dies.

Her great teal-skinned carcass plummets to the depths of the ocean.

She strikes ground three thousand meters below the water surface. No sunlight ventures here, but life continues to hum along (albeit with somewhat reduced vigor) in this pitch-black benthic universe, where water pressures can run up to an astonishing 300 atmospheres (that is, 300 times the pressure exerted by the overlying column of air at sea level) and photosynthesis is impossible. Adult whales attain weights that range between 30 to 160 tonnes and, upon their death and fall, represent a significant input of biomass for the carbon-starved lower reaches of the ocean. In fact, the dead and decaying body of a whale can sustain a mini-ecosystem of opportunistic deep-sea scavengers over a period of decades. Within a month, the body will be swarmed over by hundreds of slimy, superficially eel-like scavengers called hagfish. The hagfish has no jaws and is instead equipped with a protrusible “tongue-like” structure that bears “teeth” (or, really, two serrated tooth-plates that are designed to grasp and draw meat into the mouth). The animal forces its head against the flesh, ties itself into a knot against the skin of the dead whale and proceeds to rasp away at the muscle tissue. Often times it only eats away as much muscle as is necessary to bore a hole into the body cavity – where it can then feast on the soft internal organs. Some hagfish seek the easy route to the viscera by entering the mouth or anus.

One of the most chilling scenes in Attenborough’s masterful documentary on the Earth’s Oceans, the Blue Planet, is deep-sea footage of wormy hagfish, “thick as an arm”, chowing down on the pale remains of a whale.

Well, that’s a pleasant image – but what do hagfish have to do with vertebrate evolution?

Hagfish are unusual creatures. For starters, they aren’t really vertebrates, let alone fish – they aren’t endowed with a vertebral column. They lack jaws. They have multiple hearts. They can absorb organic matter through their skins, not unlike several lower invertebrates. They bear two simple eye spots which can detect differences in light levels but cannot, as far as we know, construct detailed images. A lot of the vertebrate innovations we take for granted are nowhere to be found in this curious organism.They do, however, posses a skull made of cartilage – and this property grants them a place within the clade Craniata, which we shall define and discuss shortly. Hagfish are one of two possible remnants of a very ancient group of so-called “jawless fish” (the latter word being used loosely in this context) that first made its appearance some 400 million years ago. Jawless fish were probably the first backboned animals to evolve cellular bone, paired fins and complex sensory systems to detect sound waves and monitor pitch, yaw and roll. They therefore represent a crucial evolutionary stage in the history of vertebrate life.

Vertebrates? Jawless fish? Craniata? What’s all this about?

It can be difficult keeping the various taxonomic hurdles that separate tunicates (sessile filter-feeding animals we discussed in a previous post) from vertebrates in mind as we move forward. But there is a logic to the madness. Let’s play God and try to construct a vertebrate from scratch.

Let’s start with a small eel-shaped organism with a series of paired muscle blocks running down the length of the body.

We need a bundle of nerve cells (and a collection of attendant supporting cells) to run along the back to carry electrochemical signals to and from each of these muscle blocks – let this be the nerve cord. We also need a rigid supporting rod to run along the back for muscle attachment and to prevent the body from telescoping when the muscle blocks contract. However, it should not be so rigid as to prohibit the body from twisting or curving at all (throwing the body into a series of lateral undulations or curves is precisely how the muscle blocks achieve propulsion). Cartilage performs this task adequately. We have just constructed the Notochord – a rod of cartilaginous tissue that runs below the nerve cord.

Since we’ve established that the earliest vertebrates were jawless creatures, our organism will have to be dependent on some kind of suction filter-feeding. We can imagine food and water being drawn into a collection sac. We shall call this the pharynx. The water can be expelled through ‘gill slits’ along the sides of the pharynx – while the food is conveyed to the gut.

In fish, it should be noted, the gill slits are richly provided with blood vessels which can extract oxygen from the departing water. The gills are also supported by a series of catilaginous gill arches.

Pretty much any organism that displays these characteristics – nerve cord, notochord, pharynx, gill slits- at some point in its life cycle (humans display these during embryonic development, many tunicates in the larval stage and lanclets in the adult stage) may be identified as a chordate. So we’re past the first hurdle. Pikaia (530 mya) is the among the earliest examples of a primitive chordate.

Pikaia, a possible primitive chordate from the Cambrian.

So we’re done with chordates, but what are craniates?

Practically no invertebrate head displays the degree of functional and structural complexity seen in the vertebrate head. Although a “front end” can certainly be identified in lancelets and tunicate larvae, there is no “head”, so to speak. The notochord extends right up to where we’d expect the head to be. The creation of the head, then, is the next step we ought to take. The anterior (or front) end of the nerve cord must be expanded into a complex brain which can wield centralized command over the nervous system. New sensory apparati and cranial nerves must be built to detect oncoming sources of food or possible predators. The earliest traces of this process can be seen in Pikaia. At some point, a cartilaginous brain case became necessary to house and protect this new equipment. We have now constructed a “craniate” – a chordate with a highly specialized head. This group contains both true vertebrates and hagfishes.

This transition was made possible by the duplication of clusters of “Hox genes” over evolutionary time by mutations. The end result of this was the creation of a special zone of tissue above the nerve cord in the embryo, the neural crest, from which cells migrate away during development to create various features important to the form and function of the brain. The origins of the neural crest – which is also associated with other “typically vertebrate” tissues like bone – is an area of active research.

And what are vertebrates?

A series of cartilaginous arches called neural arches running along the length of the back evolved to provide for further muscle attachment and protection of the nerve cord. A complementary series of inverted arches called centra was added to this design. A neural arch plus a centrum constitutes a vertebra. The vertebral column consists of a series of articulating vertebrae. In vertebrates, this segmented backbone replaces the notochord during embryonic development.

We’ve been speaking of cartilage thus far, but what of bone?

The next great evolutionary leap in this story is the appearance of a hard mineralized tissue called bone. Many complicated explanations for the emergence of this hugely important verebrate characteristic have been formulated. It is worth remembering that many invertebrate groups have evolved hard mineralized tissues – consider, for example, the armor of crustaceans or the calcium carbonate shells of mollusks. The formation of bone involves the secretion of a matrix of long chain sugars and fibrous protein by certain cells (called Osteoblasts) and the consequent deposition and crystallization of calcium phosphate in this matrix, hardening it. The general pattern of this process is roughly mirrored in invertebrates that build exoskeletons and shells, but with different cells, matrix components and minerals. In a sense, vertebrates have two skeletons: an outer dermal (exo)skeleton and an endoskeleton constructed from either cartilage or bone. Of the former, little remains in humans outside of the skull. Dermal bones are formed within the skin and are derived from the dermis, a skin layer beneath the epidermis.

The earliest bones were dermal bones. A cartilaginous endoskeleton was probably already in place by the time bone made a real appearance in craniate anatomy. Cartilage does not usually make it into the fossil record unless it is particularly dense and thus our knowledge of the skeleton that supported the tail and trunk of the earliest fishes is wanting. The dermal bones we will deal with in the next section, on the other hand, are far better preserved and shaped out some of the most extraordinary heads in all of vertebrate history.

The endoskeleton in most extant vertebrates is composed of non-dermal bone derived from cartilage. The beginnings of this type of bone, called endochondral bone, can also be seen in later jawless fish.

Even in primitive Jawless fish, bone comes in two flavors: cellular and acellular. These types are essentially the same in terms of matrix composition, but differ in that cellular bone has cell-spaces for bone forming cells. The dermal bones of these early fishes consists of a lower compact and closely layered base of acellular bone, a middle layer of spongy cellular bone and an overlying later of dentine projections.

So why did fish evolve bones?

1) Bone might have initially served as a storehouse for phosphate and calcium. Calcium plays a massive role in cell signalling and in maintaining osmotic pressure in the body. Phosphate plays a similarly major role in cell metabolism and the generation of energy. By maintaining steady levels of these ions, marine jawless fish might have been able to venture into brackish or fresh waters with lower calcium or phosphate levels without experiencing any physiological distress. They could make withdrawals from or deposits in their calcium phosphate “banks” as necessary.

2) Bone can serve as a protective casing for delicate sensory apparati or viscera. One rather picturesque suggestion from some workers in the field is that bone evolved in early fishes in response to predation from giant sea-scorpions called Eurypterids in the Ordovician seas. Early fish are often described as “armored” for good reason.

Other suggestions point to bones as being beneficial for swimming in some way and/or for the functioning/insulation of a set of electrosense receptors.

When and where did the first fish evolve?

The earliest fossil fish (which can incontrovertibly be identified as such) dates to about 430 million years ago – a period in the earth’s geologic history known as the Ordovician.

Astraspis was a jawless fish with two far-set eyes and a bony “head shield” made up of a number of solid plates. It is a little strange to think of a vertebrate with no movable bony mouth parts to speak of – jaws are, after all, central for the feeding behavior of most backboned animals, from sharks to elephants. The trunk of the body was covered in small overlapping scales. A large number of gill openings may be found on the sides of the head shield. This structure bears a few other holes – two for the eyes, one for the nostril and one for a third eye or pineal organ. The pineal organ was sensitive to light levels but used a mechanism of photoreception that was different from that of the other two eyes. The pineal organ is actually visible in some modern animals, including certain amphibians. The animal is roughly torpedo shaped, a design that limits drag.

It must be noted here that Hagfish lack bony parts and therefore represent a condition that is even more primitive than this.

These early fish – called ostracoderms – appear to have dwelt in warm, shallow seas on the margins of the continents (the supercontinent of Gondawanaland is sometimes posited as the cradle of ostracoderm evolution). Deeper sediments yield numerous invertebrate fossils, but no examples of ostracoderms – suggesting that they were incapable of swimming across stretches of open ocean. In terms of ecological niche, many ostracoderms appear to have been somewhat closer to the lowly tribolite than to modern carp or tuna. The position of the mouth on the underside of the body (as well as various details of the skull anatomy) seems to indicate that they were bottom-feeders, sucking up detritus and other organic matter and burrowing into the sediment. The true patricians of this era were eurypterid scorpions and giant squid-like nautiloids. BBC’s Walking with Monsters had a decent scene depicting an encounter between a school of Cephelaspis and a mighty eurypterid.

How diverse were Ostracoderms?

As in other vertebrates, the structure of the skull can be used to divvy up Jawless Fish (ostracoderms) into a number of taxonomic categories.

1 – Astraspis, an early jawless fish, 2 – Hemicyclaspsis, 3 = An Anaspsid, 4 – 2 Heterostracans

One group is the Heterostracans. Their head bones include one bony plate on the top, the bottom and on each set of gill slits. The water isn’t expelled through individual slits, but through two vents at the back of the skull. These were the first fishes to invade freshwater.

During the Ordovician, the earth experienced a massive glacial episode that locked up large amounts of water in ice-sheets, reducing global sea levels. New lanes of shallow water opened up between the continents – and the ostracoderms may have taken advantage of that to distribute themselves across the world’s oceans.
Among the heterostracans, which were at their height in the following Silurian period, we see numerous experiments with horn-like structures that may have helped stabilize the organism, anchor it to the sea bed or stir up food particles. They did not have paired fins behind their heads and were probably clumsy swimmers in comparison to most modern fish.

While the tail and posterior half of the body were covered in small scales, granting the body some measure of flexibility and the tail the ability to undulate and generate propulsion, the weight and dimensions of the head shield probably made stable directional swimming a difficult affair (think of how difficult it is to push a heavy cart from behind and keep it on course!). This would not have been a serious impediment anyway, given that many of these creatures probably spent most of their lives wriggling about on the sea floor.

Some jawless-fish, like Hemicyclaspsis, a member of the Osteostraci (yet another group of jawless fishes), were optimized for bottom feeding in terms of body shape.  It had two closely-set eyes and a large roof of solid bone  covering the head (with a fairly low slope from the rim of the head shield to the eyes). The flatter the organism, the lower the pressure differential between the top and bottom. This reduces lift – meaning that the organism has to expend less energy trying to stay close to the bed.

Hemicyclapsis also sports two paired fins and many complex bits of sensory hardware – a proto-nose, a proto-ear and the rudiments of a lateral-line system for detecting movement and vibration in the surrounding water. A line of sense receptors (probably chemosensory or electrosensory) is located on the head shield. Water was forced into the pharynx by the act of swimming – this allows for water to pass through the gills. This sort of respiration, called “Ram respiration”, means that the fish would asphyxiate if it ceased to move for a sufficient time period.

The structure of the brains of some jawless fish can be inferred from studying the thin outlines of cartilage-derived bone that enveloped many of the soft organs of the head. Reconstructions reveal a primitive brain similar to that of lampreys and hagfish. It can be partitioned into a fore, mid and hindbrain.

This is a simplified sketch of an Ostracoderm brain cast. I have omitted lots of extraneous detail.

Not all jawless fish were bottom dwellers. Anaspsids, for example, were scaly streamlined jawless fish with paired fins that could feed on suspended food particles – possibly algae. The skull is not weighty – there is no head-shield – and anaspids may have been active swimmers. They may be ancestral to the modern lamprey – which is not covered in scales, but in skin. There are traces of a circular cartilage with surrounds the mouth – a condition similar to what is observed in lampreys. The lamprey and the hagfish are the only two surviving jawless fish.

Illustrations of some jawless fish resemble surrealist works of arts. Some of these fish have heads shaped like flying saucers, screwdrivers and vacuum cleaners. Many of these adaptations have no modern analogue and their precise functional significance may remain unknown forever. Some of them had rod like bony processes that could be used to suck up food particles. Others had huge dorsal crests or eyes set apart like headlights. The diversity of forms is massive and one gets the sense that we’re trying to reconstruct a lost opera from just a few notes. What is clear is that the jawless fish were successful in terms of both distribution and longevity – after all, they lasted into the geological epoch during which the first fish were making that giant leap onto land.



Elephant Evolution
May 21, 2011, 5:10 pm
Filed under: Uncategorized

NOTE: Hurrah! I have returned!

Tusk met tusk on the arid fields of Rafiah, Palestine in 217 BC. Alexander’s great empire had fallen into the hands of a number of feuding successor dynasties that ruled all the known world between Macedonia and the Punjab. Syria was a disputed border-land between the imperial domains of two princes in particular, Antiochus III and Ptolemy V. Antiochus, who would later challenge the rising Roman superpower and acquired the epithet “the Great”, approached from the east with 62,000 infantrymen, a few thousand horsemen and over a hundred war elephants. Ptolemy fielded similar numbers of men, horses and elephants. The signal was given and the elephant contingents charged at one another. Antiochus’ Elephants were of Indian origin, while Ptolemy’s were North African. The ground rumbled and dust clouds leapt into the air as they thundered across the sand.

Things turned sour quickly. The North African elephants, spooked by the strange smell of their subcontinental adversaries – from whom they were separated, evolutionarily speaking, by a space of 7.6 million years – suddenly began to panic and retreat, throwing Ptolemy’s right wing into a dreadful rout. Greek troops fought in a closely-knit military formation called a phalanx, where the mobility of a single soldier was severely limited. It’s difficult to imagine the sheer horror of being stuck in a box of shields and spears while a 4 ton animal rampages towards your position, tearing through ranks of armed men with ease. The Battle of Raphia, as the engagement came to be known, is generally regarded as one of the largest elephant battles in the classical world.

Elephants were used to break formations and wreak havoc by many generals in the ancient world: most famously by Hannibal, who hurled them at the Roman legions – with varying degrees of success- during the second Punic War. The Romans themselves would later make use of elephants, albeit in far reduced numbers, against Celtic armies in Iberia and Britain.

Apart from their use as instruments of war, Elephants have been – in various times and places – objects of reverence, beasts of burden and symbols of imperial might. The caliph Harun-al-Rashid  gifted an albino elephant named Abu-Abbas to Charlemagne as a token of friendship. Legend has it that Charlemagne later called upon Abbas in a tremendous battle against the Viking Danes. That’s epic.

Depictions of Elephants from medieval Europe

Elephants were, apparently, quite mysterious to the writers of medieval bestiaries. They have this to say about the subject:

“They possess the quality of mercy. If by chance they see a man wandering in the desert, they offer to lead him to familiar paths. Or if they encounter herds of cattle huddled together, they make their way carefully and peaceably lest their tusks kill any animal in their way.” – Aberdeen Bestiary, 1200 CE.

 “There is an animal, which is called “elephant,” which possesses no desire for sexual intercourse … They live 300 years.” – Harley MS 3244, 1255 – 1265 CE

This one is trippy:

“Between elephants and dragons is everlasting fighting, for the dragon with his tail bindeth and spanneth the elephant, and the elephant with his foot and with his nose throweth down the dragon, and the dragon bindeth and spanneth the elephant’s legs, and maketh him fall, but the dragon buyeth it full sore: for while he slayeth the elephant, the elephant falleth upon him and slayeth him.” – Batholomaeus Anglicus, 13th century CE.

In fact, male Elephants have an incredible libido; have been seen killing livestock, live for about 60 years and only occasionally engage dragons in mortal combat.

Elephants … and Hyraxes?

Unlikely relatives: From left to right, a Hyrax, a Dugong and an Elephant

Bizarrely, the closest living relatives of modern Elephants are Dugongs, Manatees and Hyraxes. The evidence for this curious relationship comes from DNA/protein sequence data and shared anatomical/developmental characteristics like the late eruption of permanent teeth and undescended male gonads. They collectively belong to the Mammalian clade Afrotheria – so named because of the African origins of the group in the middle Cretaceous. Elephants belong to the subgroup Proboscidea, an order of animals that, until a few thousand years ago, inhabited a wide range of terrestrial environments across the globe – from icy tundra to tropical rainforest.

The tree of Elephant evolution

Where and when did Elephant evolution begin?

The Proboscidea seem to have begun their divergence from the Sirenia (the group containing manatees and dugongs) in the Eocene along the swampy shores of the Tethys sea (now the Mediterranean rim) at sites like modern-day Fayoum, Egypt, where fossil specimens of the two groups can be found in close proximity to one another.  Global temperatures were much higher then than they are today and there were no ice-caps at the poles at that time.

Among the earliest members of the order Proboscidea was a hippopotamus-like creature named Moeritherium that lived about 35 million years ago. It had short,  stout  legs,  a long body and a short tail. The animal probably spent a great deal of time wading through swamps and riverine habitats, consuming fresh water-vegetation. It had two pairs of short tusks which, like the tusks of modern Elephants, were simply modifications of the second incisor. Tusks are the longest teeth in the animal kingdom!

They have trunks?

Moetherium had a flexible upper lip for grasping food, a sort of “proto-trunk” similar to what we see in modern tapirs. The trunk or “Proboscis” of an Elephant is a combination of the nose and the upper lip. The existence of a trunk in a fossil species can be inferred from the size and position of the nasal opening and the structure of a bone canal below the eye socket (called the infraorbital canal) which conveys nerves and blood vessels to parts of the face – in the case of elephants, to the trunk. The trunk is a phenomenal multi-purpose tool that can be used for everything from the delicate handling of branches to siphoning up water to drink.

Is Moetherium ancestal to the modern elephant? 

Semi-aquatic habits are seen in a number of early Proboscideans and many of them bear superficial resemblance to the modern tapir. Moeritherium is probably not a direct ancestor of the Elephantidae (which includes all living Elephants), but an offshoot on the family tree that has left no living descendants.

Paleomastodon, a possible ancestor of both mastodons and elephants and a close relative of Moeritherium, also had two pairs of the tusks. The lower pair was shovel-shaped and possibly used to scoop up freshwater plants. The trunk is more obvious in this species than in the roughly contemporaneous Moeritherium.

Paleomastodon

Mastodons? Are those like Mammoths?

Mammutidae is a major Proboscid family that (probably) owes its ancestry to Palaeomastodon.  It includes the iconic woolly Mastodon – which occupies a somewhat august position in the history of Paleontology as one of the earliest large fossil species to have its anatomy fully reconstructed and exhibited to the public. Thomas Jefferson used the past existence of the mighty Mastodon on American soil as an argument against the (primarily French) notion of American Degeneracy, the goofy idea that atmospheric conditions in the New World weakened both men and animals – making them smaller and less intelligent. It’s easy to confuse Mastodons with Mammoths, but the two are actually only distantly related and the superficial similarities between them are more the result of convergent evolution than any phylogenetic affinity. Mastodons were shorter than mammoths and had stockier legs. They browsed on shrubs and the crowns of their molars had pointed cusps for clipping leaves. The high crowned molars of mammoths were better suited for grinding down grass. They had longer and less curved tusks. They both survived to the end of the Ice Age and faced predation from human beings.

So, we’re done with proto-elephants – what sorts of Proboscideans have appeared since?

The order Proboscidea is notorious for its incredible experiments in tusk shape and length. A rapid proliferation of forms took place in the Miocene, producing shovel-tusks, downward curving tusks and a number of other strange parodies of the conventional spiral curved elephant tusk. We will deal with three major branches that evolved in the midst of this diversification, the Gomphotheres, Stegodons and Deinotheres.

From left to right: Deinotherium, Platybelodon (a shovel-tusked Gomphothere) and Stegodon

Deinotheres thrived during the Miocene. Some of them attained heights and lengths that dwarfed modern elephants. The best known of them, Deinotherium, stood at a shoulder-height of about 3.5-4.5 meters, making it about as tall as a double-decker bus. It is the third largest land mammal known to science. The build of its skull and its dentition was so unusual that it led one anatomist to suggest that it was an aquatic beast that anchored itself to the riverbed with the aid of its tusks. Deinotheres lack any upper tusks, but they sport a pair of dramatically downward-curving tusks that may have been used to dig up food or as a sexual display. The lower jaw is itself bent downwards and lacks any canines. The retracted facial and nasal bones also seem to indicate that these animals had trunks. Deinotheres were never very diverse and the only evolutionary trend they seem to display within the family is a general increase in size.

The Gomphotheres represent a diverse collection of elephant-like animals that appeared on the scene in the Miocene. They originated in Africa and radiated out throughout Eurasia and the New World. They bear four substantial tusks, two upper and two lower. Some specialized forms developed shovel-shaped lower tusks that might have been used to scrape up plants for consumption.

Modern elephants posses a gland called the “musth” gland on the side of the face that produces chemicals during heightened sexual activity. These chemicals are associated with agitation and violent outbursts – and elephants in musth on an elephant farm are usually kept under lock and chain because they have an increased likelihood of going on a stampede. The musth gland first appears in the Miocene and can be inferred in fossil species from the shape of the sides of the skull.

One common feature among shovel-tusked Gomphotheres is a long lower jaw – something that contrasts strongly with the greatly reduced lower jaw of modern elephants. A short, strong neck was necessary to hold the head and dental apparatus up.

Both Stegodonts and modern Elephants are derived from Gomphotheres. Stegodonts differ from Elephants in the structure of their teeth, but generally resemble modern Elephantidae. A pair of vestigial tusks remained in the lower jaw. The upper tusks were long and nearly touched the ground. In an interesting case of island dwarfism, one species of Stegodon seems to have undergone a dramatic reduction in size on the Indonesian island of Flores. It is comparable in size to a small water buffalo. Interestingly, they lived contemporaneously with a species of dwarf Hominid named Homo florensis (often dubbed “Hobbits”) on the same island. And, while Homo sapiens took on Mammoths in Eurasia and North America, hobbits may well have speared and killed pygmy elephants in the tropical mists of Flores (evidence to this effect has been uncovered).

A number of general trends can be observed throughout the course of elephant evolution:

1) A general increase in size

2) The loss of teeth. The typical mode of replacement of teeth seen in most mammals (including ourselves) was abandoned for a system where older worn out teeth in the front of the jaw are replaced by newer teeth from the back of the jaw – rather like a conveyor belt. The old tooth drops out or is swallowed. Each half-jaw of an adult elephant bears upto three teeth– the foremost one on its way out and the hindmost one on its way in. An elephant will run through 6 or, if it’s very lucky, 7 sets of molars in its life time. The destruction of the final tooth means certain death.

3) An increase in the complexity of teeth and the length and diameter of tusks.

4) A transition from browsing to grazing that roughly coincides with the spectacular rise of grasses across the planet as CO2 levels and global temperatures dipped in the Miocene.

By 11,000 BC, Gomphotheres still roamed the forests of South America, Mastodon herds still rolled across the frozen wastelands of North America and Stegodons could still be found in island forests in Indonesia. In fact, there may have been well over a dozen Proboscidea species on the planet when Humans first started migrating out of the African continent. Unfortunately, there are barely 3 species left today. In the next post, we’ll deal with the Elephantidae: the Wooly Mammoth, the Asian elephant and the African elephant.



A Paleo podcast
August 5, 2010, 2:59 pm
Filed under: Uncategorized

 I’ve been a podcast junkie for well over 2 years now. I think it’s a fabulous way of packaging and communicating complex information to a wide audience. I’ve learnt a lot about the History of the Roman Empire, American politics, Philosophy and Astronomy by downloading and listening to 10-40 minute long audio-shows. They’re put together by a diverse lot – professors, enthusiasts, college-students, school children, former radio talk-show hosts, journalists etc.

Truth be told, I’d rather sit through a poorly-executed podcast than a badly written blog entry. I’ve tried rummaging through the wastelands of the science podcastosphere in search of a Paleontology podcast of some sort. So far, I’ve only located this one: This Week in Dinosaurs. It lasted for a single episode. So R.I.P TWID, I guess.

This is my plea: If you’re a Paleo-person (and I include professionals and enthusiasts alike under this umbrella) of any kind and have the time, equipment and expertise to host a Paleontology podcast, please do consider doing so. I’m willing to hazard that there’s a large community of hobbyists and amateurs out there just waiting to get their hands on such a show. I’d be glad to help/promote in any way possible.

EDIT: Turns out that there is a non-defunct Dinosaur podcast show out there: http://www.dinorama.net/ Awesome!



Evolution of the Felidae, part 1
July 29, 2010, 12:11 am
Filed under: Uncategorized

NOTE: Some geological periods that might need some defining: Pleistocene = 2.5 million to 12,000 years ago, Pliocene = 5.3 to 2.5 million years ago, Miocene = 23 to 5.3 million years ago.

Evolution of the Cat Family

An ancient forest. Enter Proailurus, the Dawn Cat. Lithe and long-backed, she flits ghost-like through the leaf-shrouded tree canopy. Boughs sway with each muffled footfall. Her silhouette blots out branch-framed dapples of forest light like a cold wind snuffing out candle flames.
She is on the prowl.
Suddenly, frightened squawks and thumping wingbeats are heard as a group of birds scatter noisily from a high-flung knot of leaves and bark. Something savage has transpired in the treetops. Proailurus has made a kill.
She descends to a lower, sturdier branch, an inert mass of feathers and flesh securely fastened in the snare of her jaws.

Proailurus is a cat*. And recognisably so. She stalked the treed valleys and flatlands of Eurasia 25 million years before the first Leopards ever did. But despite this yawning temporal chasm, they share a number of important characteristics: binocular vision, a pair of highly specialized blade-like “carnassial” teeth designed for shearing meat, retractable claws, a short face (compared to Dogs and Bears) and an almost exclusively carnivorous diet (known as “hypercarnivory”). These features are common to all cats.

The Leopard is, however, substantially larger than the caracal-sized Proailurus and there are differences in the morphology of the teeth, limbs and vertebral column between the two species (and, more broadly, between the Ur-cats and modern cats) that we will discuss in some detail as we move along. For example, Proailurus had more teeth than modern cats do.

The body proportions of Proailurus are strikingly similar to those of the Fossa, a cat-like predator that is found exclusively in Madagascar. Like the modern Fossa, Proailurus was (probably) an accomplished tree-climber. It had short, grasping forearms, supple ankles capable of wide rotation and long, propulsive hind limbs. Check out this video of a Fossa to get an idea of how Proailurus might have moved about in the canopy.

* The taxonomic position of Proailurus has recently been the subject of some debate. Some studies argue that it belongs to the Felidae (the cat family) and was ancestral to all later cats, whilst others contend that it belongs to a group of animals that was ancestral to mongooses, civets and hyenas in addition to the true cats. I have decided – for the sake of simplicity- to stick to the orthodox view and call Proailurus the earliest known felid.

The next link in the chain of cat history is Pseudaelurus. The fossil genus was given that name in 1850 by Paul Gervais, an illustrious French zoologist who seems to have dabbled in everything from the study of Dinosaur eggs to fish stocking. The classification was based on a single mandible that had been described over a decade earlier by another Frenchman and scientific heavy-weight, Edouard Lartet. Lartet likened the mandible to that of a Hyena, noting that it sported more teeth than the standard-issue felid jaw bone.

I'm not even going to pretend like that's to scale, but it does illustrate one major trend in Cat Evolution: the loss of teeth. This is associated with "hypercarnivory".

Since then, Paleontologists have identified a dozen species of Pseudaelurus. So here’s a description to chew on:

Pseudaelurus was a genus of agile wildcat-to-cougar sized felines that roamed Eurasia, Africa and North America 20-8 million years ago. Their skeletons are very similar to those of modern big cats.

Pseudaelurus bore certain “primitive” features, including short metapodes (these bones are equivalent to the “hand” and “foot” bones), hind limbs longer than forelimbs and a long, flexible back. It was more successful than Proailurus in terms of geographical distribution; Pseudaelurus fossils have been reported from places as far apart as Nebraska, USA and  Ash-Sharqīyah, Saudi Arabia.

Green spots = Pseudaelurus finds, Red spots = Proailurus finds. It's not entirely accurate, but it's good enough.

It was, ostensibly, the first cat to immigrate into the New World. It did so by crossing a land bridge that connected Eastern Siberia to Alaska during the early Miocene (the bridge itself has the wonderfully Tolkienesque name of “Berengia”).

The metapodes of Psuedaelurus are elongated compared to those of Proailurus, but shorter than those of modern cats. This suggests that while it was better adapted for locomotion on the ground than its fossa-like predecessor, Pseudaelurus was still (as also indicated by the structure of its heel bone and the nature of the padding between its toes) quite tied to life in the canopy. As the felids descended from the trees and adopted more “cursorial” lifestyles, the metacarpals and radius elongated. This elongation of the lower forelimb (radius+metacarpus) is greatest in the Cheetah – the most cursorial of all the big African cats.

The Cheetah and Pseudaelurus forelimb. Notice how the forelimb of the former is elongated. This is an adaptation for cursoriality. The humerus-to-radius ratio in Pseudaelurus is indicative of an arboreal lifestyle.

Unlike the Cheetah (and like Pseudaelurus), the Clouded Leopard and the Jaguar have short radii and metacarpals. This increases the grasping strength of their arms – an adaptation for scaling trees and sinuous branches.

Two magnificent feline dynasties trace their origins to a common Pseudaelurus ancestor. One line bought the farm just 11,000 years ago, whilst the other continues to persist, if somewhat tenuously, in the present era.

A cat evolution cartoon

Here we hit an evolutionary fork in the road, with the Sabre-toothed cats on one side and the “normal” conical-toothed cats on the other.

 The Saber toothed cats (Machairodonts)

A poster from the Roland Emmerich movie, "10,000 BC". The Saber-toothed cat depicted here is hugely exaggerated in size.

Saber toothed cats are, beyond a shadow of an inkling of a doubt, the most popular prehistoric mammalian carnivores in current times. Try to initiate a conversation with the words “Hey, I saw a Homotherium skeleton on display at the Museum!” and you’re likely to get blank stares. But pad a similar sentence with the wonderfully picturesque adjective-noun combination of “Saber-toothed cat” and ears perk, eyebrows arc – you might even elicit a disinterested “Oh?”

And hell, IMDB tells me that they’ve made about 6+ film appearances. Granted, nearly all of the motion pictures they’ve featured in are decidedly craptacular, but that’s 6 more movies than the Creodonts or the Bear dogs will ever get.

Here’s a quote from a (deservedly obscure) 2002 television film titled “The Saber-tooth”:

Trent Parks: We got to get out of here.
Casey Ballenger: Where’s Lola? Trent, where is she? You left her behind?
Trent Parks: It had her. There was nothing I could do. It’s one of those dinosaurs.
Casey Ballenger: What?
Trent Parks: Those tigers with the teeth.
Casey Ballenger: A sabretooth?
Bob Thatcher: What?
Leon Tingel: You’re talking crazy, man. They’re extinct.

Ah yes, “Those tigers with the teeth”. Painfully amateurish screenwriting aside, let’s spring the question: Is the Saber-toothed tiger ancestral to the modern Tiger? And furthermore, was it manifestly bigger than what passes for ‘Tiger’ these days?

The answer to the first question is no. The Tiger and Saber-toothed “Tiger” lines diverged in the Miocene with Pseudaelurus and the two groups aren’t particularly closely related. Nor is there any reason to think that Saber-toothed “Tigers” had striped coats.

As for the second question: Well, it depends. We will take the term Saber-toothed “Tiger” (a vague and unfortunate misnomer that we will hereafter dispense with) to mean the genus Smilodon. Smilodon comes in three flavours. Smilodon gracilis, Smilodon fatalis and Smilodon populator. The largest extant felid, the Siberian Tiger, was certainly heavier that S. gracilis. Predicted body mass values for S. fatalis range between 160-280 kg, making it comparable to the Siberian Tiger (usually 220-260 kg, although a few exceed 300 kg) in terms of size. And the South American Smilodon populator was enormous even by Tiger standards, with the largest specimens weighing in at over 400 kg. A quote from Christiansen and Harris (2005):

Smilodon populator is clearly one of the largest felids ever discovered, rivaled only by the giant Pleistocene North American lion (see Merriam and Stock, 1932; Anyonge, 1993; Turner and Anton, 1997), and even normal-sized individuals are predicted to have rivaled world record Siberian tiger males (see Wood, 1976; Nowak, 1991; Sunquist and Sunquist, 2002).

A sketch of Smilodon populator I did. Coat colour is unknown. It is similar to Homotherium in one major way: It had longer forelimbs than hindlimbs. Some general features are also marked.

But Smilodon was not the only Saber-toothed cat. It belongs to a large group of felines with elongated upper canines called the Machairodontinae. This group includes two major tribes, the Smilodontini (Dirk-toothed cats, including Smilodon) and the Machairodontini (Scimitar-toothed cats). I will mark Smilodontini species in blue and Machairodontini species in green.

Some of the earliest known Saber-toothed felids were quite similar to Psuedaelurus – Paramachairodus ogygia, for example, was a primitive leopard-like saber-toothed cat with robust fore limbs and a supple body. It appears in Europe (Spain) during the late Miocene alongside the much larger Machairodus aphanistus. The latter had elongated limbs compared to the Psuedaelurine form, indicating a transition to a more terrestrial lifestyle. It was a top predator in its day and, as far as we are aware, the first Machairodont to attain Lion-size. Its skull morphology reflects a mix of adaptations to the biting model of modern cats and that of later Saber-toothed cats. Interestingly, canine size in this species appears to differ greatly between the sexes. Canines play an important role as weapons in male combat and confrontation (principally over females and territory). Among modern cats, Leopards and Lions display the greatest sexual difference in canine size and, concurrently, male members of both species exhibit low levels of tolerance for other males of the same species. By inference, we may argue that male competition was intense in Machairodus aphanistus too.

So how did P. ogygia and M. aphanistus interact? This is an interesting question. Modern small-sized felids actively avoid encounters with larger felids (as is the case with Leopards and Lions) in areas where they coexist. This is often accomplished by refuging in the tree cover or hunting at times of day when larger competitors are inactive. The Cheetah, for example, hunts during the daytime, when Lions are least active. The Leopard preferentially occupies wooded portions of the environment where Lions are unlikely to venture. A similar dynamic may have existed between the arboreal P. ogygia and the more terrestrial M. aphanistus.

Now let’s leap forward in geological time to the Pliocene era, 3 million years ago, when the Lion-sized Homotherium, a possible descendant of Machairodus, was present alongside the smaller Jaguar-like Megantereon in many parts of the world. These later Saber-toothed taxa share some important features:

1)       A long, powerful neck, presumably for reaching the underbelly or throat of struggling prey.
2)       A shortened lumbar spine.
3)       A shortened tail.

There were differences between Homotherium and Megantereon too. For one, the former had high shoulder blades and longer forelimbs than hind limbs, giving it a stance not unlike that of a Hyena. These long forelimbs were not quite as muscular as those of the modern Lion and seem to have been better geared for long-distance running rather than swatting down large prey. Megantereon, on the other hand, had relatively short and stocky forequarters.

NOTE: What follows is overwhelmingly based off of a single paper: Anton et al. (2009). There are, of course, considerable differences of opinion regarding the narrative I’ve constructed below, so take what I say with a grain of salt.

One species of Homotherium, H. latidens, occupied a particularly broad temporal and spatial range in Eurasia and Africa, coexisting in various places and times with some of our own Hominid relatives. It first broke into Europe after a cooling event 3.2 million years ago, alongside Megantereon cutridens. The two species exploited different habitats and prey niches – with the scimitar toothed H. latidens tracking and preying (possibly in packs) on large migratory animals on the open plains and the dirk-toothed M. cutridens stalking riverine forests and woodland patches for moderate-sized prey. This state of affairs persisted for 2 million years.

Europe found itself on the receiving end of another cold and dry event 1 million years ago. Although climate change had initially facilitated Megantereon’s entry into the continent, it was now mopping up forests and replacing them with open, high-visibility grasslands, thereby depriving the cat of its usual prey sources and hiding places. Competition from migrant Hominid populations and other predators eventually drove Megantereon to extinction.

Homotherium latidens weathered the changes a little better, persisting into the late Pleistocene. However, it now shared the European “preyscape” with two formidable competitors: The Lion and Homo heidelbergensis, a possible ancestor of the Neanderthal. Giant, aggressive Hyenas of the genus Pachycrocutus also appeared on the scene.

The European lion (left) and the slightly smaller Scimitar-toothed cat, Homotherium (right), coexisted in Europe during the Pleistocene.

H. latiden’s lacklustre performance in the face of competition from the European Lion can be attributed to one major factor: It was a specialist.

A compelling body of evidence suggests that it was heavily dependent on large, grazing mammals as a food source and worked in packs to bring them down. The replacement/extinction of various ungulate species in Europe as a consequence of climate change may have dealt a blow to Homotherium populations. New herbivore populations would display new body-size ranges (prey size is a major determinant of hunting success) and employ new predator-avoidance strategies.

As Europe’s climate oscillated between cold and warm conditions throughout the middle and late Pleistocene, versatility became key to survival. Long-term success hinged upon being able to operate in both closed forest (associated with warm, moist periods) and open plain environments. So how might  Homotherium have performed in these alternating episodes of steppe and forest vegetation, particularly in times of scarcity?

Arid spells on the plains would, naturally, be marked by an increase in inter-species competition for food resources. Cover on the open plains would also be reduced. Kills made by packs of H. latidens on the open plains would quickly draw attention from other major predators. It is not difficult to imagine a Lion pride driving a group of Homotheres away from a kill (Hyenas regularly lose kills to Lions on the Serengetti). On an individual versus individual basis, the European Lion outstripped Homotherium in terms of sheer muscle power and size. This sort of kill-stealing or kleptoparasitism (perpetrated by Lions and perhaps Hominids and Hyenas) may have effectively put H. latidens out of business.

Warm periods would have been characterized by more heavily forested environments. The typical grazing mammals that constituted the bulk of the Sabre-toothed cat’s diet would have been reduced in number. Ambush hunting would have been the name of the game in the woodlands. So how does Homotherium measure up as a solitary Ambush hunter preying on a large proportion of relatively small game?

Lions readily operate as ambush hunters when forced to live in forested areas. They thrived in all phases of the Middle and Late Pleistocene thanks to this facility.

H. latidens was incapable of the accelerated bursts of speed that modern cats, including the Lion, use to ambush and kill prey. It was an endurance runner rather than a sprinter. It is therefore unlikely that Homotherium would have made much of an ambush predator. And the specialized H. latidens may have had trouble tackling smaller prey, given the potential damage its long, latterally-flattened canines could incur in the process. Extant felids, however, can apply a bite to the nape or skull of a smaller animal without risk of injury to their rounded-section canines.

The European Lion was the dominant felid predator in Europe for hundreds of thousands of years, surviving until historical times. The youngest recorded Homotherium fossil – from the North Sea – dates to about 28,000 years ago, some 17 centuries shy of the invention of agriculture.

In North America, however, Homotherium (H. serum) and the American Lion shared their environment with a third felid, Smilodon fatalis. We have discussed the three species of Smilodon above. Of these, Smilodon fatalis is the best known. Enormous numbers of S. fatalis bones have been recovered from the La Brea tar pits in Los Angeles. Many of them reveal some kind of pathological condition – dental disease, genetic abnormalities etc. There is also evidence of injuries sustained during combat with other cats.

We will deal with Smilodon, the morphology of the tooth and skull among cats and the hunting strategies of the Saber-toothed cats in the next post.

References:

“Phylogenetic Systematics of North American Pseudaelurus (Carnivora: Felidae)” by Tom Rothwell, American Museum Novitates, 2003
“The Big Cats and Their Fossil Relatives” by Alan Turner and Mauricio Anton.
“Body size of Smilodon” P Christiansen, JM Harris – Journal of Morphology, 2005
“Co-existence of scimitar-toothed cats, lions and hominins in the European Pleistocene. Implications of the post-cranial anatomy of Homotherium latidens (Owen) for comparative palaeoecology”  – M Antón, A Galobart, A Turner – Quaternary Science Reviews, 2005
“Late Pleistocene survival of the saber-toothed cat Homotherium in Northwestern Europe” – JWF Reumer, L Rook, K Van der Borg, K Post, Dick Mos, John De Mos – Journal of Vertebrate Paleontology, 2003.
“Inferred behaviour and ecology of the primitive sabre-toothed cat Paramachairodus ogygia (Felidae, Machairodontinae) from the Late Miocene of Spain.” – MJ Salesa, M Antón, A Turner, J Morales. Journal of zoology, 2006.



Heads up!
July 14, 2010, 10:24 pm
Filed under: Uncategorized

 NOTE: This post is of a somewhat personal nature. Skip to the final two paragraphs if you want to see the crux of my message. 

I try to bring all of my abilities/affectations/personality disorders to the table here at Fins to Feet – I write, I organize, I sift through research papers and I’ve even dabbled in some technical drawing. But I think I can do a little more.

  Before I made this website – before I even left high school – I used to spend many a restless night wandering the catacombs of cyberspace in search of freeware game-design systems. It has always been a burning ambition of mine to author a game-system of some sort. When I was a younggin, the medium of play was utterly irrelevant to me: I didn’t care if my game was executed on sodden cardboard sheets or on MS DOS. It was the idea that was central.

  I first had a crack at game building in 2003, when I and a neighbourhood friend (both aged 11 at the time) designed a goofy chess-variant with leaping rooks and club-totting cavemen. I even managed to get it published in the Chess variant pages – something that astonishes and befuddles me to this day, considering how singularly unchesslike the game really was. In the succeeding years, I made custom trump-card games (based, in chronological order, on insects, predatory cats, dinosaurs and Marvel/DC superheroes), partook in pen-and-paper romps through fantastical battlefields with my high-school compatriates and eventually shored on the wide banks of the interwebs with my first online “game” (and I had an accomplice in this too) in early 2006.

 And here my desire to develop a game hit a fundamental roadblock: I could not program. Even my more computer-savvy peers (many of whom are now fluent in two or more Computational languages) were only beginner coders at the time. And thus, we had to devise all sorts of artifices to circumnavigate the “programming phase” of our various game-development projects. I tried to learn how to use Game Maker, a scripting-free game-development tool that is still roaringly popular with lazy, wannabe developers like my former-self, but failed to ever release a fully functional game on it. My attempts to fashion games with other freeware development tools were similarly unsuccessful. I was at an impasse.

 We then grudgingly moved into the realm of text based gaming. But even here my troubles with basic programming drastically truncated my options. Finally, we ended up building RPGs and Strategy games centered around Mailing lists and online forums – a process that entailed absolutely no programming skills. Some of these projects were, in a word, embarassing. Others are glorious symbols of my early adolescence. The last time I logged onto or was active on any one of these projects was well over 2 years ago.

 So why do I subject you to this tale of incompetency and unsated ambition? Well, because I’m going take up the challenge once more. And I have fresh armaments. I’m going to design a mostly-but-not-exclusively-text-based educational game on the early evolution of the Aves as part of the Taking Wing series. It will be hosted online – no downloads neccessary. It’ll be a sort of simulation of a “Prehistoric Aviary” where you can amble around, yell at the customer service and, of course, oggle at, interact with and learn about various extinct bird species.

I sometimes like to pretend like I have somethin akin to an actual readership on this blog, so I’m going to throw this question out to you folks: Is there any early bird or feathered dinosaur in particular that you’d like to see in the simulation? You can respond in the comment box below or via E-mail (visit the “About me” page to find it).

Thanks for reading!