Cenozoic birds and reptiles The Cenozoic (also Cainozoic or ...

Cenozoic birds and reptiles 

The Cenozoic (also Cainozoic or Cænozoic – which means new life) was 

an era when many terrifying animals evolved: there were the entelodonts (the 

hell pigs see below), which I wrote about in my last post; 

Source: http://i33.tinypic.com/ml3769.jpg 

large carnivores like andrewsarchus (see below), which I also wrote about in earlier posts; 

Source: 

http://scienceblogs.com/tetrapodzoology/Stuart%20Brooks%201992%20Andrewsarchus%20 

animation.jpg

sabre-toothed cats (see below, also covered in an earlier post); 

all manner of herbivores, both large and small: some from now-extinct lineages, some whose 

descendents are still around today like elephants, horses, deer, etc; 

Source: 

http://attachments.conceptart.org/forums/attachment.php?attachmentid=378319&d=121192 

9283

large carnivorous reptiles like pristichampsus, a 3-4 metre long terrestrial crocodile which 

probably hunted fleet-footed animals like the diatryma as shown in the image (see below); 

Source: http://www.geol.umd.edu/~jmerck/bsci392/lecture33/pristichampsus.jpg 

and terrifyingly large, predatory birds, which are collectively known as ‘terror birds’. 

Source: http://thefallen17.files.wordpress.com/2008/08/11653769.jpg

It was the era when grasses (which may have evolved somewhat earlier) began to 

radiate outwards and cover vast tracts of land. Because they grow from the root end, rather 

than from the tip end, they can survive far more intense grazing, and are thus capable of 

providing an abundant source of food for hordes of grazing animals, which in turn were what 

the staggering array of predators fed upon. These grasses also clad the vast tracts of savannah, 

and stimulated the evolution of the running animals such as the horse family (equidae). 

Source: http://activity.ntsec.gov.tw/lifeworld/english/content/images/en_evo_c6.jpg 

The above graphic illustrates the lineage of modern horses, but is a bit misleading as there 

were all manner of other equids which are not represented here, some from species which are 

still with us today like zebras, donkeys and the like, others from species now extinct like 

quaggas, and a whole slew of prehistoric forms. 

rce: http://www.mun.ca/biology/scarr/139409_Equid_evolution.jpg 

Sou

It was also when the two American continents joined up, to the detriment of South 

America’s marsupials, many of which went extinct, but which then allowed North American 

animals to invade the continent, and to evolve into new forms there. 

Source: http://www.geo.arizona.edu/Antevs/ecol438/exchpan1.gif 

It was not only the time when the two Americas joined up though, it was also the time 

when the land-masses, which are constantly on the move (I shall be writing a post about this 

process called plate tectonics in due course), reconfigured themselves more or less into the 

forms they have today, leading to massive climatic changes throughout the planet – when the 

two Americas joined up for instance, the Atlantic Ocean’s temperature dropped, and during

the Oligocene, after the tectonic creation of Drake’s Passage (which separates South America 

from Antarctica), the climate cooled significantly due to the advent of the Antarctic 

Circumpolar Current, which brought cold Antarctic water to the surface. In fact, generally 

speaking, this era (the Cenozoic) could be characterised as a period of long-term cooling. 

Source: 

http://www.sciencemag.org/content/vol292/issue5517/images/large/se1619374001.jpeg 

So, all in all, it was a time of many changes in the history of life on the planet, and a 

time when for quite a while the dominant predators were reptilian (large lizards and terrestrial 

crocodiles), and avian (large birds, some of which were flightless). 

By the way, though we, mammals call this the age of mammals, in reality it ought to 

be called the age of birds, because avian forms outnumbered the mammalian ones two to one 

at least. Snakes also enjoyed a period of massive speciation during this era, partly because

their chief prey, the rodents, also diversified greatly during this time. Another significant 

evolutionary feature during this time was the co-evolution of flowering plants and insects, 

which continued to develop the evolutionary co-dependence they had pioneered earlier, and 

which I wrote about in a previous post. 

Anyway, getting back to the main subject for this post, as far as the birds went, there 

was a gigantic eagle, Haast’s eagle, which evolved in New Zealand, and which hunted moas, 

which were enormous flightless birds. There is even some folkloric and not well substantiated 

evidence that these eagles attacked and ate humans, as the Maori have stories of a bird, called 

the pouakai bird, or the hokioi, which descended from the sky to kill and eat people. 

Some people have speculated that this eagle was also the inspiration for the roc bird in 

the story of Sindbad the sailor (which features in the 1001 nights, as recounted by Shahrazad / 

Scheherazade), but the connection seems to me tenuous at best – though Marco Polo does talk 

of a rukh bird, and it is possible that Chinese seafarers could have picked stories of this New 

Zealand bird up from the various Malayo-Polynesian sailors who were around in the South- 

East Asian ports frequented by the Chinese at the time. For my money, the roc of Sindbad is 

more probably inspired by the Malagasy Crowned Eagle of Madagascar, which almost 

certainly fed on the enormous elephant birds (see below) and on the vaguely human-like 

lemurs, and with which Arab and Persian sailors might have had contact. 

Haast’s eagle (and possibly the Malagasy Crowned Eagle) were the only eagles ever to 

be the top predator in their respective ecosystems. 

Source: 

http://tyrannosaurusversusspermwhale.files.wordpress.com/2009/11/giant_haasts_eagle_atta 

cking_new_zealand_moa.jpg

Haast’s eagle terrifying though it may have been to Maoris, was unimpressive when 

compared to the various, and diverse species of flightless, but fleet-footed predatory birds of 

the open grasslands. Almost all of these ‘terror birds’ evolved and lived exclusively in South 

America before the two continents were connected by what was much later to become the 

bane of Teddy Roosevelt’s geo-politicking efforts – the isthmus of Panama. 

Source: http://scienceblogs.com/grrlscientist/2007/01/terror_bird_arrived_in_north_a.php 

Titanis walleri is a member of the Phorusrhacid family and was one of the larger 

predatory bird known to have existed. It weighed approximately 150 kg, had powerful legs 

and feet and a head somewhat larger than a man's. It stood perhaps 2,5 metres tall. Had you 

been walking around on the plains of South America a couple million years ago, and had you 

met one of these birds, it would likely have been a singularly unpleasant experience for you 

(though perhaps not for the bird, as it would probably have made a meal out of you). 

They were swift runners, and like ostriches, emus and cassowaries, could probably 

deliver a lethal slashing kick with their claw-tipped feet. T. wallerei fossils have been found 

in both N. and S. America, and have been dated to a time before the land-bridge between 

these two continents was established. It is unclear how this bird, which evolved in S. 

America, got across to N. America and ended up going as far as Texas and Florida, where its 

fossilised remains have been found. It might possibly have island-hopped, swimming between 

the various volcanic islands which lay between the two approaching continents, or it may 

have rafted across on floating vegetation, but the precise method by which it crossed over is 

still unclear.

Source: http://www.paleocene.com/paleocene_photographs.html 

Phororhacos longissimus was a giant prehistoric terror bird. This drawing is by 

Charles R. Knight and was published in Animals of the Past, 1901. Phorusrhacids (family 

Phorusrhacidae) or terror birds were large carnivorous flightless birds that were the dominant 

predators in South America, from about 62 to about 2 million years ago.

Source: http://www.paleocene.com/paleocene_photographs.html 

This is one of the diatrymas, birds which stood over two metres tall, and had unusually 

large skulls in proportion to their bodies (nearly 50 cm long, including a beak over 20 cm 

long.) They weighed about 100 kg. Diatrymas bear a superficial resemblance to phorusrhacids 

(previous image), but there is not a close relationship. There has been some debate about 

whether diatrymas were carnivores or herbivores, using their large beaks for cracking nuts 

and large seeds much as parrots do today. Lawrence Wittmer and Kenneth Rose however 

concluded from an analysis of the biomechanics of the jaw in 1991 that the birds were 

carnivorous, hunting and eating small mammals. 

Source: 

http://i223.photobucket.com/albums/dd138/subzero9285/Titaniswallericlawhandedgoodrecon.jpg 

 

Note the ‘hands’. Some reconstructions of certain terror birds, like B. burmeisteri above, 

have endowed them with these appendages. We just don’t know for sure.

Source: http://www.scielo.br/img/revistas/paz/v43n4/17491f1.gif 

The largest terror bird was the gargantuan Brontornis burmeisteri (the largest of the 

birds in the illustration above), which stood nearly 3 meters, tall and weighed as much as 400 

kilograms, making it possibly the 3 rd heaviest bird ever to have lived, after Aepyornis 

maximus (the flightless elephant bird of Madagascar, ca. 450 kg), and Dromornis stirtoni ( an 

Australian prehistoric flightless bird also known as the mihirung bird, ca 500 kg, see below), 

which was another flightless predatory bird with a powerful beak and jaw, though presumably 

not closely related to the S. American terror birds. 

Source: http://en.wikipedia.org/wiki/Dromornis_stirtoni

Source: http://en.wikipedia.org/wiki/Aepyornis The elephant bird of Madagascar, which 

stood over 3 metres tall (so a 2 metre human standing next to this bird would just come up to 

the base of its neck), displayed together with its egg, which had a circumference of just over 

a metre! This animal was one of the many species to have gone extinct as a result of contact 

with humans. Whatever the opposite of the Midas touch is (the Sadim touch?), we certainly 

seem to have it as far as biodiversity and ecology are concerned. 

As I mentioned earlier, during much of the time that terror birds walked the Earth, 

South America was an island continent, and its unique cargo of species evolved in isolation 

from the rest of the world. Then, three million years ago, the two American continents were 

connected. This allowed North American predators, such as jaguars and sabre-toothed cats, to 

invade South America, where they outcompeted the remaining terror-bird species, driving 

them to extinction. 

Relatively little is known about the life-styles of the terror birds. Since there are no 

large, flightless carnivorous birds alive today, scientists cannot observe and extrapolate from 

them, and must instead turn to observations of the smaller flightless carnivorous birds, like the 

secretary bird of Africa, and the seriema of S. America to garner clues as to how the large 

birds might have behaved. One big problem with this approach is that neither the secretary 

bird, nor the seriema is the top predator in its ecosystem, but the terror birds probably were, so 

behavioural extrapolations are likely to be tenuous. In addition, few complete terror-bird 

fossils have been unearthed, thus complicating matters even further. 

Researchers still do not know if terror birds hunted in groups – as velociraptors 

(bipedal dinosaurs who share a similar body shape) are thought to have – or alone, as jaguars 

or tigers do today. That they were meat-eaters is fairly certain, based on the form and 

structure of their beaks, which resemble those of predatory eagles and scavenging vultures.

Understanding the running speed of terror birds could shed some light on many 

aspects of their hunting behaviour. Speed is very important for predators that pursue prey in 

open country. It's not only relevant for chasing prey, but also for colliding with more 

momentum with the prey, in order to inflict greater damage. In addition, high speed not only 

enables carnivores to catch a wider range of prey but allows them to surprise and confuse 

their victims more readily. This minimizes the chances of a potentially risky counterattack. 

We know that some of the prey-species of the terror birds may have preyed on were heavily 

armoured. The armadillo-like glyptodont, for example, was the size of a small car, covered in 

plates of body armour, and equipped with a hefty tail club, so high momentum and surprise 

could have played significant roles in hunting these animals. 

Based on mathematical models, we do have some estimates of the maximum running 

speed of the terror birds: The modelling results indicate that some terror birds were capable of 

running at around 50-60 kph (which is about as fast as modern ostriches can run). 

Source: http://i.telegraph.co.uk/telegraph/multimedia/archive/00628/news-graphics- 

2006-_628930a.jpg 

More striking though are the calculated results for Mesembriornis (above), a 10- 

million-year-old terror bird species that weighed around 70 kg. It may have been able to run 

at close to 100 kph, which is more-or-less as fast as a cheetah – the fastest terrestrial animal 

today – can run. This figure though is not accepted by everybody, and there is still much 

discussion about how realistic it is. One thing is for sure, Mesembriornis had very strong leg 

bones, so an alternative explanation for this may be that this particular terror bird used its legs 

to practice karate on its prey, kicking them to death. They may also have used their kicking 

abilities to crack open the long bones of their prey, in order to access the bone-marrow, which 

is a very nutritious food-source. 

There are many things left for us to learn about these amazing birds, and fresh ways of 

thinking about palaeontology are taking us in exciting new directions. Aside from the terror 

birds, there were also some rather impressive predatory lizards around during this period, the 

largest of which, without doubt, was megalania, and I shall now turn to look briefly at these

animals before concluding this post. 

Source: http://www.unexplainedaustralia.com/images-content/Megalania.jpeg 

Megalania, also known as the Giant Goanna or Monitor Lizard was an Australian 

reptile, which existed at least 40,000 years ago in mainland Australia. Early Aboriginals 

would no doubt have encountered megalania in their peregrinations around the islandcontinent. 

The size of the animal based on fossil records, indicate that it was a reptile of about 

7 meters length, with a maximum conservative weight of approximately 1940 kg. It was the 

largest land dwelling lizard to have ever lived. It has often been likened to the Komodo 

Dragon but it is genetically related to the Perenite a large Goanna found west of the Great 

Dividing Range. 

Megalania would have mostly fed upon medium- to large-sized animals, including any 

of the giant marsupials like diprotodon along with other reptiles, small mammals, birds their 

eggs and their chicks. It had heavily built limbs and body and a large skull complete with a 

small crest in between the eyes, and a jaw full of serrated blade-like teeth. It may have 

scavenged as well as hunted. It is also possible that it killed and ate human beings until it 

went extinct. 

Studies have shown that other members of the genus Varanus, such as the Komodo 

dragon and Lace monitor possess venom glands in their jaws, as well as having extremely 

bacteria-rich mouths, so it has been suggested that other varanids (group of carnivorous 

lizards), including megalania, are likely to also have possessed similar glands. 

Some Cryptozoologists claim that megalania still exists in remote parts of Australia. 

Sightings have been reported as recently as the 1990's in New Guinea as well as in Australia, 

but I remain sceptical.

Cenozoic birds and reptiles The Cenozoic (also Cainozoic or ...

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