How did aquatic dinosaurs go extinct?

How did aquatic dinosaurs go extinct?

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Dominant theory is that 'normal' dinosaurs went extinct from ether super volcano or meteor impact or combination of both. However there were aquatic dinosaurs that are not present at this day. Was it one of the events above that caused them to go extinct, or was it something else?

How did aquatic dinosaurs go extinct?

Spinosaurs (like Spinosaurus) are currently only known from 112-97 million years ago, although isolated teeth push the origin possibly back to ~150 Mya. At least now, there isn't any definite spinosaur material younger than 97 Mya.

So spinosaurs were already extinct when the rest of the non-bird dinosaurs went extinct at the end of the Cretaceous, whether by meteor impact, volcanism, a combination, or something else completely.

Not a lot of people realize how extreme and how sudden the dinosaur's extinction was. Radiolab did an episode with several geologists about the extinction of the dinosaurs. Basically, when the meteor hit the Earth, a humongous amount of material was ejected into space, and most of it fell back down to the surface all around the planet. As it fell it left an incredible amount of heat in the air, raising temperatures to as high as 1200 Farenheit (650 Celsius). Anything too large to hide under dirt died (dirt is a surprisingly good insulator). Even plankton and animals near the surface of the ocean would have been decimated by the heat, destroying the food chain that supported the large mesosaurs and plesiosaurs. The whole process is thought to have taken 2 hours. The fact that anything lived through that at all is dumb luck, and even if a semi-aquatic dinosaur was deep enough to avoid the worst of the heat, the food supply would have been destroyed and they would have starved shortly after the impact.

How Did Mass Extinctions Like Dinosaur's Death Shape Earth’s History? Here Are 5 Examples

For the past 10,000 years, Earth has been at the forefront of the extinction crisis rapidly eradicating animals worldwide. Scientists define mass extinction in The Conversation as the extinction of three-quarters of all animals within a minimum geological time frame of fewer than 2.8 million years.

Species became extinct regularly. According to the American Museum of Natural History, scientists estimate that at least 99.9% of the plant and animal species that have ever existed are now extinct. Just a few times in the history of this world have mass extinctions arisen, in which at least half of all animals perish in a brief time. The five mass extinction events are listed below.

Kids Feedback: What Happened to Megalodon and Other Sea Creatures?

This is actually a question from my 9 yr old son. He is constantly asking me things I cannot answer and his new obsession is the Flood & the animals. He wants to know why certain animals don’t exist now. Did the flood do something? For instance, the Megladon, why isn’t there one now, when Great Whites are a smaller version of it and they are still around? Are Great Whites possibly Megladons, changed over time (not evolution, just God-ordained change)? What about “dinosaur-type” animals, like Plesiosaurus or others like it? How did these water animals not survive the flood? My son constantly asks me questions like these. We are as active as we can be with AiG books,videos and such, but I just can’t seem to answer them all. I told him he should have asked Ken himself when we saw him last weekend. If there is an answer to this, we would love it. I have looked over the website and found a question about fresh/saltwater fish & their survival issues during the flood.

– G.C., Tennessee

Thanks so much for sending in all of your son’s questions! Let’s start with the general questions about flood survival. Your son was wondering if large “dinosaur-type” sea creatures survived the Flood. Some of these creatures did survive, but many also died. The Flood was incredibly turbulent and violent. Genesis 7:11 states, “In the six hundredth year of Noah’s life, in the second month, the seventeenth day of the month, on that day all the fountains of the great deep were broken up, and the windows of heaven were opened.” The flood waters and related geological catastrophes changed the entire planet, and we still see evidence of those changes today.

The mid-ocean ridges are evidence of the catastrophic plate movements during the Flood. This massive scar—the largest geological structure on earth—is a sobering reminder of God’s judgment on past sin.1

The following quotation, taken from the Answers magazine article “World Underwater,” describes possible destruction caused by the Flood.

In the 1980s, creation physicist John Baumgardner developed a theory for the rapid motion of the earth’s crust during Noah’s Flood. His theory suggested that, within a few short weeks, the crust beneath the pre-Flood oceans sank 1,800 miles (2900 km) to the base of the earth’s mantle. This suggests that continents moved rapidly during the Flood and that the Flood occurred thousands of years ago, just as the Bible suggests.2

Given the massive destruction caused by the Flood, it’s easy to see why many sea creatures did not survive. The fossil record confirms the massive destruction that took place during the Flood. Both land and sea creatures are found buried together in “fossil graveyards” throughout the world.2

However, many of the large “dinosaur-type” sea creatures did survive. The Bible describes both dinosaurs and large sea creatures existing after the Flood. Job 40:15-24 describes a dinosaur called behemoth, with a tail like a cedar tree. Job 41:1-34 describes a massive, fire-breathing sea creature called leviathan. There are also many legends and other accounts of human interaction with dinosaurs and dinosaur-like sea creatures after the Flood.3 Native Americans in Utah drew petroglyphs, or drawings, of dinosaurs.4

So why don’t we see sea creatures such as leviathan today? Some of the sea creatures that were common in pre-Flood oceans struggled to survive after the Flood. These creatures may have become extinct, or nearly extinct, due to factors such as climate change, food shortage, disease, predators, and even overhunting by humans. This continues to be a problem that we see today, with several animals on the edge of extinction.

Your son also had questions about megalodon and the great white shark. The megalodon was actually a very large type of shark. Just as we observe many types of sharks in our oceans today, megalodon was a type of shark that was very common in pre-Flood oceans. In fact, megalodon could possibly still exist today!

The largest known carnivorous fish to have inhabited the sea is the Carcharodon megalodon. Based on the discovery of huge fossil teeth, scientists believe the megalodon (which means giant tooth) was a huge shark that could have been up to 17m (60 feet) or longer (nearly twice as long as a Great White) . . . . Several alleged eyewitness sightings of enormous sharks over the years suggest these colossal creatures may still inhabit our ocean depths. This would sit comfortably with the Bible, but less so with evolutionary ideas.5

I hope this answers all of your questions. For more information, please read the following articles:

Parents, if your children have any questions, please submit them using the “contact us” section on our main website.

Why did the dinosaurs become extinct? Could cholecalciferol (vitamin D3) deficiency be the answer?

Palaeontological deductions from the fossil remnants of extinct dinosaurs tell us much about their classification into species as well as about their physiological and behavioural characteristics. Geological evidence indicates that dinosaurs became extinct at the boundary between the Cretaceous and Paleogene eras, about 66 million years ago, at a time when there was worldwide environmental change resulting from the impact of a large celestial object with the Earth and/or from vast volcanic eruptions. However, apart from the presumption that climate change and interference with food supply contributed to their extinction, no biological mechanism has been suggested to explain why such a diverse range of terrestrial vertebrates ceased to exist. One of perhaps several contributing mechanisms comes by extrapolating from the physiology of the avian descendants of dinosaurs. This raises the possibility that cholecalciferol (vitamin D3) deficiency of developing embryos in dinosaur eggs could have caused their death before hatching, thus extinguishing the entire family of dinosaurs through failure to reproduce.

At the end of the Cretaceous era, about 66 million years ago (Mya), there was a mass extinction of many animal species around the world, including the large and diverse family of dinosaurs. The challenge of explaining this huge loss of biological diversity has been the province of geologists and palaeontologists. Their expertise in dating rocks and in reconstructing the characteristics of these long-gone life forms, from fossil bone and tooth fragments, is a remarkable achievement of scientific observation and analysis. Nevertheless, there has not been unanimous agreement in interpretations amongst these expert investigators. Because, from the vantage point of the present, the extinction of such a vast range of species seemed to have suddenly occurred, the concept has been proposed that some catastrophic environmental change is a unifying hypothesis to explain their disappearance. Some investigators, on the other hand, suggest that the time frame of the process of extinction from a biological viewpoint was very long and that the various species had declined in number over many generations. The conflict between catastrophism and gradualism to describe the process of extinction has been debated extensively during the second half of the 20th century.

The case for a catastrophic cause of mass extinction was strengthened by the discovery of a worldwide enrichment of the rare element iridium in a narrow band of geological strata formed 66 Mya ( ,1 ) . The source of that iridium was proposed to be from a huge asteroid or comet that collided with the Earth, coinciding with the time of the mass extinctions ( ,2 – 4 ) . The discovery of the Chicxulub impact crater in the Yucatan Peninsula on the Gulf of Mexico confirmed, from its size and structure, that a large celestial object had collided with the Earth at the time that the mass extinctions had occurred ( ,5 ) . The consequences of that impact would indeed have been catastrophic, not just in the geographic region around the impact site, but worldwide because of environmental changes from an atmospheric dust and aerosol cloud that would have remained for years in the stratosphere ( ,2 ) .

Those who favour a gradual decline towards extinction of all species of the dinosaur family, except the ancestors of modern birds, have some plausible arguments. The dating of fossils of all known dinosaur species is incomplete and is only well established for a range of dinosaurs in North America. It has been argued that long-term environmental changes had diminished the number of species over millions of years before the asteroid or comet impact, particularly the large-bodied Saurischian and Ornithischian dinosaurs ( ,6 ) . Careful review of fossil records of both classes of dinosaurs has indicated that the number of species was in decline over millions of years. Thus the family Dinosauria would have been susceptible to extinction by a range of environmental changes to which they could not adapt ( ,7 ) . Nevertheless, others have concluded that there is little evidence for a gradual decline worldwide in the diversity of dinosaur species, in contrast to that in North America, over the long term before the fossil record indicated that all non-avian dinosaurs had become extinct ( ,8 ) .

Although the debate between the gradualists and the catastrophists appears to be still unresolved, both groups of palaeontologists do agree that the dating of dinosaur fossils ended in the era of the Chicxulub impact event. Even if the diversity of dinosaur species had been in decline, the gradualists do acknowledge that the worldwide environmental changes caused by that impact could have led to their final extinction.

Clearly the effect of the asteroid or comet collision would have been devastating to all life forms in a wide geographical region around the impact site. The proposed environmental changes that would have occurred worldwide include a period of dim sunlight because of solar radiation absorption by ejected particles and aerosols in the atmosphere and stratosphere. Consequently, there would have been a short-term temperature drop ( ,9 ) , which, together with diminished sunlight, would have inhibited or killed photosynthetic plants. However, perhaps a more significant effect, as far as the dinosaurs were concerned, was a consequence of the geological site of impact. The Chicxulub site contains vast amounts of limestone (CaCO3), anhydrite (CaSO4) and gypsum (CaSO4.2H2O) ( ,10 ) as well as hydrocarbons ( ,11 ) . A result of the asteroid impact would have been the ejection into the stratosphere of particulate carbon soot, CO2 and sulfate aerosols ( ,12 ) . This would have had a marked cooling effect on the climate from the absorption of much solar radiation. Because such geological sites that are rich in sulfur and carbon deposits are not plentiful, it has been suggested that if the asteroid impact had occurred in most other regions of the world, the probability of mass extinctions would have been much less ( ,11 ) .

Conclusions about the biological effects of the Chicxulub impact have focused on the undoubted environmental changes of temperature, light intensity, sea temperatures, sea levels and climate disruption in the months and probably years following the impact. The implications of these changes are that a consequent restricted food supply for many life forms that disappeared would have contributed to their extinction.

One result of the asteroid collision with Earth, that has not been considered from a biological perspective, is a particular effect from the ejection into the stratosphere of the sulfur aerosols. There are various calculations of the amount of sulfur, as sulfate or SO2, based on estimates of the size of the impacting asteroid and the density of sulfur deposits at the impact site. One estimate is that 326� gigatonnes of SO2 were distributed globally in the stratosphere ( ,13 ) . Another, in broad agreement, put the quantity of stratospheric SO2 in the range of 200� gigatonnes ( ,10 ) . The effect of such quantities of SO2 on global climate can be deduced from observations on the changes from sulfur ejected into the upper atmosphere from volcanic eruptions ( ,14 ) . As an example, the Tambora eruption in Indonesia in 1815, the largest volcanic event in the past 200 years, produced only about 0뜕 gigatonnes of stratospheric SO2. Yet in the following 12 months, this relatively small amount, compared with that from the Chicxulub impact, had a noticeable cooling effect on the world climate ( ,10 ) .

An alternative environmental catastrophe postulated as the cause of dinosaur extinctions is a series of vast volcanic eruptions in India which created the Deccan basalt larval floods, known as the Deccan Traps. It has been argued that the timing of this volcanism is more likely to have been associated with the demise of the dinosaurs than the Chicxulub impact event ( ,15 ) . Nevertheless, geological evidence puts the timing of the Deccan volcanism and the asteroid collision so close together that it has been suggested that the Chicxulub impact actually triggered the largest of the volcanic eruptions which gave rise to the Deccan Traps ( ,16 ) . Although volcanic activity in general has not been considered to produce stratospheric sulfate aerosols in the quantities anywhere near that of the Chicxulub impact, the Deccan volcanism may have been an exception. Calculations from paleomagnetic measurements in a Deccan basalt escarpment identified single eruptive events, the largest of which could have released quantities of SO2 over years or decades, comparable with that released by the impact at Chicxulub ( ,17 ) . Together, from volcanism and the asteroid collision, the SO2 emitted into the stratosphere could have had a prolonged climatic effect that would have lasted for years.

One biologically significant property of stratospheric SO2 is that it strongly absorbs solar UV light in the UVB wavelength range of 290 to 320 nm. In the steady atmospheric state of the present-day era, the intensity of UV light reaching the Earth's surface is attenuated by ozone ( ,18 ) . However, the UVB-absorbing power of SO2 is 2୵ times greater than that of ozone ( ,19 ) . The traces of SO2 from human activity such as that emitted by cities has a limited effect on UVB at ground level ( ,20 ) . However, the mass of stratospheric sulfur from the Chicxulub impact, perhaps combined with that from the Deccan volcanism, would have been sufficient to completely block UVB reaching the Earth's surface for a decade or longer ( ,13 ) .

One of the effects of UVB radiation is that it acts on 7-dehydrocholesterol in cells of the superficial integument of terrestrial animals to make, by a photochemical reaction, the pre-hormone, cholecalciferol. A characteristic of animals that depend on solar UVB radiation to supply cholecalciferol is that its precursor, 7-dehydrocholesterol, the penultimate metabolite in the synthesis of cholesterol, accumulates in superficial skin cells. In other cells, its concentration is very low because of rapid conversion to cholesterol. Cholecalciferol is more popularly known as vitamin D3 but under natural conditions it is not a nutrient. The food of most animals contains, at most, only traces of cholecalciferol. An adequate supply of cholecalciferol can therefore only be obtained by exposure of skin to UVB radiation from the sun. A deficiency of cholecalciferol causes a range of pathological changes, the most prominent of which is the bone disease of rickets or osteomalacia.

Much of the knowledge about the metabolism and function of cholecalciferol was obtained in the mid-20th century from studies of the domestic chicken (Gallus domesticus), a member of the avian descendants of the dinosaur family. Like the extinct dinosaurs, modern birds reproduce by depositing eggs encased in a hard shell of crystalline calcium carbonate. The egg shell not only protects the developing embryo inside, but it also is the source of Ca to mineralise the bony skeleton towards the end of the incubation period. Thinning of the egg shell from dissolution of calcium carbonate also weakens it, so that pecking by the beak of the chicken at full term fractures the shell, allowing the chicken to emerge.

Early in the development of knowledge about the biology of cholecalciferol, it was observed that hatchability of domestic hen eggs produced during winter was low, particularly if the laying hens had been kept indoors. Hatchability improved when hens were directly exposed to sunlight in spring ( ,21 ) . It was therefore postulated that cholecalciferol, incorporated into yolk during egg production, was an essential requirement for avian embryonic development. When hens, reared away from sunlight, were fed a diet containing no cholecalciferol, the embryos in the eggs they produced died at 18� d of embryonic life, just before the 21-d scheduled time of hatching ( ,22 ) . Likewise, the embryos in eggs from cholecalciferol-deficient turkey hens died at day 26� of their somewhat longer incubation period of 28 d ( ,23 ) . Embryos in eggs from hens deprived of cholecalciferol developed hypocalcaemia and low bone mineralisation compared with embryos from hens fed a diet containing cholecalciferol ( ,24 ) . From this pathology it was suggested that the embryos were unable to mobilise Ca from the shell and that the consequent hypocalcaemia caused muscle weakness which prevented the chicken from breaking the egg shell ( ,24 , 25 ) .

The yolk of bird eggs, in contrast to other biological material, is quite rich in cholecalciferol. This is surprising because the yolk substances are derived from blood circulating through the ovary of the laying hen and the majority of cholecalciferol molecules in blood are in the form of its metabolite, 25-hydroxycholecalciferol, the precursor of the hormone, 1,25-dihydroxycholecalciferol. 25-Hydroxycholecalciferol has a long residence time in blood in comparison with its parent cholecalciferol which, after diffusing from its site of formation in the skin, is rapidly removed from blood by the liver. A specialised form of a cholecalciferol-binding protein transfers the trace cholecalciferol from blood into the developing yolk follicles in the ovary ( ,26 ) .

In recent years there has been much interest in the many thousands of whole fossilised dinosaur eggs and egg shell fragments found around the world. Most attention has been directed at identifying the dinosaur species of each egg type and in drawing conclusions about the reproductive strategies from the arrangement of groups of eggs and of fossilised dinosaur embryos or juvenile dinosaurs that had died after hatching. In comparison with fossil dinosaur bones and teeth, little attention has been devoted to determining the age of the fossilised eggs and shell fragments. In his comprehensive book on dinosaur eggs, Carpenter ( ,27 ) catalogued the era of sites around the world where fossilised eggs had been discovered. There were twenty sites where eggs of the Jurassic era (130� Mya) were located and twenty-eight sites with eggs from the early Cretaceous era (100� Mya). However, most fossilised eggs have been dated from 187 sites of the late Cretaceous era (66� Mya). Despite considerable palaeontological study of the eggs, some containing fossilised embryos, the question does not seem to have been asked as to why so many eggs of this extinct family have survived for analysis over 66 million years. Why did so many whole eggs become fossilised? Were the eggs infertile or did the embryos die before hatching?

A study of Hypselosaurus dinosaur eggs from southern France and the Spanish Pyrenees concluded that shell thickness was abnormally thin in up to 90 % of the samples ( ,28 ) . By comparison with egg biology of modern birds, the thinning of the shells was attributed to abnormal hormonal control of the calcification process, as a result of environmental stress. Strangely, as a possible explanation, there was no mention of cholecalciferol deficiency which is a well-established cause of thin shells in eggs of the domestic hen ( ,29 ) .

Apart from shell thickness, another feature of dinosaur eggs that has been explored is the length of incubation. By remarkable deductive analysis it has been concluded that the incubation times of eggs of various dinosaur species are longer than those of their descendant modern-day birds. Lee ( ,30 ) estimated the metabolic rate of embryonic dinosaurs in comparison with that of birds and crocodiles and concluded that dinosaur egg incubation times were up to 76 d. However, Erickson et al. ( ,31 ) , by measuring the growth lines in fossilised dinosaur embryo teeth estimated, more directly, the incubation times of dinosaur eggs. On the presumption that dinosaurs, like modern birds, were endothermic, they deduced that dinosaur egg incubation times were at least twice as long as those of birds, being up to 171 d, which is comparable with those of eggs of poikilothermic modern reptiles. Using this tooth growth-line technique, Varricchio et al. ( ,32 ) calculated that the incubation time of a theropod dinosaur (Troodon formosus) was 74 d compared with an average avian incubation time of 44 d.

Even if female dinosaurs had sufficient 25-hydroxycholecalciferol in their bodies to produce the hormone 1,25-dihydroxycholecalciferol to allow egg shell formation in the oviduct, unless they had a daily input of cholecalciferol to incorporate into the yolk being laid down in ovarian follicles, the eggs would have contained insufficient cholecalciferol to meet the needs of embryos during their prolonged period of incubation. The cholecalciferol-deficient dinosaur embryos, like those of the modern birds would either die during development, or else just before hatching. Although environmental changes leading to failure of food supply would certainly threaten the survival, over years or decades, of the wide variety of dinosaur species, the most effective mechanism of extinguishing the dinosaur family altogether would be one that prevented reproduction. One could speculate that if the modern bird descendants of theropod dinosaurs were today unable to obtain cholecalciferol from their environment, then over a short period of time they too would become extinct from reproductive failure.

Of course, if reproductive failure because of cholecalciferol deficiency was the cause of all dinosaur species becoming extinct, why then did other terrestrial vertebrates survive and evolve into the animals we know today? It is apparent that modern birds do not have a storage mechanism for cholecalciferol. Could other animals, such as mammals, have developed a means of conserving cholecalciferol to allow its many functions to continue when the environmental supply ceased? Present-day nocturnal mammals which seldom are exposed to solar UVB radiation seem to be able to maintain the functions of cholecalciferol without any apparent input from its formation in skin. There is evidence that the ancestors of modern mammals at the time of the dinosaurs had a nocturnal lifestyle ( ,33 ) . By being both viviparous and nocturnal they may have avoided the reproductive failure of egg-laying dinosaurs. It is also possible that some dinosaur species survived the catastrophic events that were associated with most dinosaur extinctions. A few species that lived within the Antarctic Circle had anatomical features that suggested they were able to see in the dim light of winter and may have died out long after other Dinosauria had become extinct ( ,34 ) . Apart from being able to see in the darkness of the Antarctic winter and accommodate to a cooling climate from the asteroid impact and volcanic eruptions, these polar dinosaurs may have also been able to conserve sufficient cholecalciferol, produced during the Antarctic summer, to maintain their capability for oviparous reproduction.

Would it be possible to test a cholecalciferol-deficiency hypothesis by further study of fossilised dinosaur eggs and embryos? Evidence could come from determining whether fossilised dinosaur embryos had bone pathology comparable with that, for example, of cholecalciferol-deficient turkey embryos that had died before hatching. Likewise, this theoretical cause of complete elimination of the dinosaur family would be supported if fossilised dinosaur egg shells, dated more exactly to the era of extinction, had the defective structure of egg shells produced by cholecalciferol-deficient birds.

In Genesis 6:19–20, the Bible says that two of every sort of land vertebrate (seven or seven pairs of the “clean” animals) were brought by God to the ark. Therefore, dinosaurs (land vertebrates) were represented on the ark.

Although there are about 668 names of dinosaurs, there are perhaps only 55 different “kinds” of dinosaurs. Furthermore, not all dinosaurs were huge like the Brachiosaurus, and even those dinosaurs on the ark were probably “teenagers” or young adults.

How long did it take dinosaurs to go fully extinct?

How much of life was vaporized on impact, and how long could those that survived the initial impact manage to live? Was it a matter of hours, days, or years or even generations before the dinosaurs fully vanquished?

Edit: I do realise birds and some other animals evolved from dinosaurs, but, as we just recently had a case of a bird species evolving itself back from extinction, let's just simplify to the big ones we all know and love from children's books and from Jurassic Park, the ones that definitely aren't around anymore :)

It looks like the dinosaurs were in decline for several million years before the impact event at Chixulub . As best we can tell the extinction of the large therapod and sauropod dinosaurs happened instantaneously, geologically speaking. That might mean days, months or even decades or more in reality rock preservation in most places does not work at human timescale resolutions.

Ir could be as long as centuries or millennia. I would personally put my money on decade to century scale with only pockets surviving the first year, and perhaps some isolated pockets lasting over 1000 years (similar to mammoth post ice age).

Edit: turns out my dinosaur knowledge was a few years out of date. Strike out the first sentence.

Edit2: Following the OP edit, /u/stringoflights adds the following and asked me to add it here for reference: Birds didn’t just evolve from dinosaurs, they are dinosaurs, and dinosaurs did not go extinct. We have more dinosaur species alive today than mammal species. It’s fine to pose a question about non-avian dinosaurs, but the fact that birds are dinosaurs is important when we are studying patterns of extinction.

The bird “evolving back” from extinction that is mentioned in the edit is an example of iterative evolution. It is absolutely not a reason to ignore an entire radiation of dinosaurs, and it’s pretty important that that misconception is corrected.

Iterative evolution means that the same or similar structures arose from the same source population at different times. It doesn’t mean the wholesale evolution of the same species twice. In the case of the Aldabra rail, which is what the edit mentions, the white-throated rail has colonized the island from nearby and evolved flightlessness more than once.

Were dinosaurs all at sea?

In the early days of palaeontology, the dinosaurs were a clear anomaly compared to other known animals (both alive and extinct). Just how could such huge creatures have found enough to eat, or even supported themselves when on land? Misunderstanding about their limbs (many people had them as lizard-like sprawlers, rather than the upright posture we now know they possessed) didn’t help, but discoveries of giants such as Diplodocus and Apatosaurus led to speculative ideas on what such bulk would mean for their biology.

One popular idea was that the larger dinosaurs lived primarily in rivers, lakes and swamps, using the water to buoy them up and quite literally take the weight off their feet. Various aspects of the anatomy of some were supposed to support this – the nostrils at the top of the head of Brachiosaurus were thought to let it breathe while it was otherwise submerged, and the deep tails of the hadrosaurs were supposed to help them swim. This general hypothesis for aquatic living was actually rather quickly dismissed in some quarters but has dragged on interminably, and even now one can still buy books that show big dinosaurs lolling in deep water and this idea also comes back around in the media periodically as well.

Certainly some dinosaurs spent quite some time in and around water. Spinosaurus and its relatives ate fish, and show isotopic signatures in their teeth that indicate they spent a lot of time in water. Plenty of dinosaurs are preserved in the sediments from ancient rivers and lakes, and while this might well have been at least in part from floods, or animals dying near water (to be preserved you generally have to be buried and that often means water), some must have been hanging around bodies of water regularly to be buried. The armoured ankylosaurs especially seem to have favoured estuaries and coastlines given how often their bones are found in deposits laid down in the sea, and others appear to have died on a shoreline or may even have drowned when crossing a river.

Aside from the obvious problem of finding enough 50 foot deep lakes for big dinosaurs to live in (in those old artworks every lake is conveniently just deep enough for them to have their heads on the surface), the biggest problem with the aquatic dinosaurs idea is that they would float! It is hard to walk around on the bottom of a lake if you are on the surface. Pretty much all tetrapods are less dense than water and you can only get so deep before your feet lift off the bottom and dinosaurs were no different. In fact the largest dinosaurs, the sauropods (these include things like Diplodocus) has numerous air-filled bones and might have floated quite high in the water.

Dinosaur footprints can tell us about their locomotion both on land, and occasionally, in water as well as revealing details about the anatomy of the foot. Photograph: Douglas C Pizac/AP Photograph: DOUGLAS C. PIZAC/AP

Even so, this would not inhibit their ability to move around when in water and it is safe to assume most, if not all, dinosaurs could swim. Very few animals are incapable of propelling themselves through the water (even if very poorly) and dinosaurs presumably did so as well. Although a number are highly controversial, there are at least some fossil tracks that show dinosaurs moving around in water. Footprints left in water show clear tracks and every toe is clearly in evidence, and then over a number of steps the prints become less and less deeply impressed in the substrate until finally there are just the tips of the claws showing, and then a return of the toes and finally whole feet. This would occur as the animal waded out, swum a few strokes with the toes barely touching down, and then on reaching the other side or perhaps a sandbar, the water was shallow enough for it to walk again and the tracks return.

Dinosaurs did then hang around water, and could swim, but how about becoming specialised as aquatic animals, such as hippos, otters or even crocodiles? Here there are few credible candidates (the spinosaurs might be one, but this is controversial), since there are a number of consistent characteristics we would expect to see in water-living animals, and they simply are not present in dinosaurs. Swimming and diving animals generally have their nostrils and eyes high up on their heads so they can see and breathe while still otherwise submerged, they generally have a streamlined body to reduce drag, a flattened and flexible tail for propulsion, and broad and spreading toes (generally webbed too) to help them swim.

Aquatic and semi-aquatic animals also tend to have more dense bones than other animals so that they do not float so high in the water, and as noted already, most dinosaurs have less dense bones than other vertebrates, so that is immediately a big strike against them being aquatic. Some dinosaurs do appear to have had retracted nostrils, but in the absence of any other features, (including raised eyes) this is hardly a great argument. Similarly, many did have deep tails, but these were not the flexible tails of swimmers, but bound together with strong tendons that would have limited lateral movement. Some also have well-spread toes, but there is no good evidence of webbing between them, and animals like hadrosaurs had hooves that would be dreadful in water or on soft ground, but ideal for walking on relatively hard surfaces.

Plenty of aquatic reptiles were in the water during the time of the non-avian dinosaurs such as this dolphin-like icthyosaur Photograph: Alamy Photograph: Alamy

The waters of the Mesozoic were teeming with reptile life though, both in the seas and freshwater environments. In addition to crocodilians and turtles and terrapins of various kinds, and more familiar animals like plesiosaurs and ichthyosaurs, at different times a huge raft of other reptiles took to the water including placodonts, phytosaurus, thalattosaurs and nothosaurs. That the non-avian dinosaurs were not aquatic animals, and do not appeared to have ever produced a real aquatic form, does seem like an oddity given their long period of life on Earth (mammals have produced the whales and their relatives, dugongs and manatees, and semi-aquatic forms like seals, otters, tapir, shrews, hippos and more all in the last 50 or so million years) though perhaps they faced strong competition at various times and simply never made it.

In short, dinosaurs were like the vast majority of terrestrial animals around today. Their habitats would have included water in the forms of rivers, lakes, and the sea, and numerous species would have needed to enter or cross bodies of water regularly. While many would have likely been capable swimmers, they were not aquatic animals spending the vast majority of their time in water, didn’t primarily eat water plants (as is seen by their strong teeth and stomach contents), and it is unlikely they used the water as a safe haven from predators. Until the birds took to the air (and indeed ventured into the water again), dinosaurs were very much creatures of dry land.

Dinosaurs – Part 1

How do dinosaurs fit into the history recorded in the Bible? Some would say, “They don’t. Dinosaurs lived millions of years before people were around. The Bible doesn’t mention them.” Dinosaurs are often used as an icon for evolution and deep time. It seems that there is no need to make a logical argument for an “old earth” – just say the word “dinosaurs” and you win! After all, we all know that dinosaurs lived millions of years ago, and some evolved into birds. Or did they?

What are Dinosaurs?

Dinosaurs are a group of land-dwelling reptiles which had some unique anatomical features that distinguish them from known living reptiles. Like all reptiles, dinosaurs were vertebrates, air-breathing, and had scales. They laid eggs, just like most extant reptiles. But dinosaurs had some features that are not found in known living reptiles – namely a unique hip structure. Modern reptiles have a hip design that places their hind legs out to the side, giving them a sprawling structure. But dinosaurs had their legs underneath their hips, giving them an upright posture. So, dinosaurs were not merely larger versions of modern reptiles, but were a unique design of reptile.

Note that flying reptiles such as the Pteranodon are not technically dinosaurs since they do not have the required hip structure. Likewise, sea-dwelling reptiles such as plesiosaurs and ichthyosaurs are not true dinosaurs because they are not land animals. However, these creatures are often included in books on dinosaurs.

Taxonomically, dinosaurs are a superorder consisting of two orders: saurischia and ornithischia. Saurischian dinosaurs are called “lizard hipped.” This name is somewhat misleading because, as mentioned above, their hips are designed for erect posture and not for sprawling. However, in saurischians, the pubis bone points forward, away from the ischium as it does in lizards. Conversely, ornithischian dinosaurs are called “bird-hipped” because they had a pubis bone that points backwards along with the ischium as it does in modern birds.

The lizard-hipped dinosaurs are divided into two main branches: Theropods and Sauropodomorphs. Theropods were bipedal and included varieties such as Tyrannosaurus rex, Velociraptor, Deinonychus, Dilophosaurus, and Compsognathus. Sauropodomorphs were quadrupeds with long necks and long-tails. They include varieties such as Apatosaurus, Brachiosaurus, and Diplodocus.

Thyreophora, Marginocephalia, and Ornithopoda comprise the bird-hipped dinosaurs. Thyreophora refers to the armored dinosaurs, such as Ankylosaurs and Stegosaurs. Marginocephalia includes both the horned dinosaurs, referred to as Ceratopsians (such as Triceratops), and the bone-headed dinosaurs (Pachycephalosauria). Ornithopoda includes varieties such as the Hadrosaurs (“duckbilled dinosaurs”), and Iguanodons.

Separating Fact from Fiction

It seems that what most people think they know about dinosaurs comes from what they have seen on television or at the movies. They “know” that dinosaurs went extinct 65 million years ago and that some dinosaurs evolved into birds because they have seen Jurassic Park. But discerning thinkers will consider the actual fossil evidence as much as possible. And since most of us don’t have easy access to these fossils and are not trained in paleontology, we rely on the experience of scientists to guide our thinking.

The most careful and discerning thinkers will also consider the worldview of any science experts, and how this might affect their interpretation of the evidence. A correct view of history can aid our interpretation of when dinosaurs lived and how they died. Incorrect views of history can just as easily hinder drawing correct interpretations of data. A paleontologist with a tenacious commitment to the philosophy of uniformitarianism will often draw very different conclusions from a paleontologist open to catastrophic processes. The fossils are the same. But different worldviews will lead to different conclusions. Understanding worldviews can help us to distinguish between what is genuinely known about dinosaurs, and what is merely conjecture, and to discern between conjectures that are reasonable and those that are unfounded.

The anatomical structure of dinosaurs has been deduced from their fossils. This is how we know their size and their approximate appearance. We know dinosaurs had scales because fossil impressions of scales have been detected in the associated rocks. Dinosaur footprints have been discovered, which tells us something about the gait of these creatures. For example, tail marks are rarely found – indicating that dinosaurs did not normally drag their tails. In some cases, we find fossils inside dinosaur stomachs, which tells us something about their diet at the time of their death. These are pretty solid conclusions because they are based on evidence and are relatively independent of a person’s view of history.

However, when paleontologists begin to speak of when dinosaurs lived, when they died, or the cause of their extinction, a person’s view of history will strongly affect his or her conclusions. Most people have heard that dinosaurs lived hundreds of millions of years ago, and went extinct about 65 million years ago. But few people know that such claims are not based on hard scientific evidence, but on beliefs about the past. Evolutionists require millions of years in order for particles-to-people evolution to sound even remotely feasible. Consequently, they interpret the geologic column (the observation that there is a statistical vertical order to fossils) as having been deposited gradually, over hundreds of millions of years. If this were so, then there can be no global flood, because such a flood could easily deposit the majority of fossils in the geologic column.

On the other hand, the Bible records a global flood in which all living, air-breathing land creatures on earth perished except for the representatives of each kind brought on board the ark. Based on the information in Scripture, we know this flood happened around 2350 B.C. If indeed this flood was responsible for depositing the majority of fossil-bearing strata, then dinosaurs cannot have died out millions of years ago, because we find their fossils in these flood sediments. So a person who embraces recorded history will draw a very different conclusion from the person who rejects history regarding when dinosaurs lived and how they died.

Most people are familiar with the secular story. Dinosaurs supposedly evolved from a Thecodont ancestor about 230 million years ago, went extinct about 65 million years ago possibly due to an asteroid impact that affected the climate. Their extinction left an environmental niche that mammals then began to fill by evolving into their various forms, continuously tracking with the environment. Some evolutionists believe that some dinosaurs evolved into the earliest birds. In any case, in the evolutionary view, human beings never saw a living dinosaur.

Far fewer people are familiar with the biblical, historical position on dinosaurs, and how it is confirmed by scientific discoveries. The Bible has demonstrated itself time and again to be the reliable, historical, Word of God. Therefore, it makes sense to embrace its history, rather than mindlessly dismissing it as so many evolutionists do. So, taking the Bible as the true history of the universe, what can we conclude about dinosaurs?

General Inferences from Biblical History

From Scripture, we know that dinosaurs are not millions of years old because the entire universe is not. This is obvious, but it needs to be stated because so many people are uninformed on this issue. God created the universe in six days and rested for one day as the basis for our work week (Exodus 20:8-11). Each day was bound by evening and morning (e.g. Genesis 1:5, 8, 13) – hence an earth rotation. Human beings were made on the sixth day (Genesis 1:26-31). The number of generations between Adam and Christ (Luke 3:23-38) corresponds to a timescale of a few thousand years – about 4000 years using other chronological information in Scripture. This puts the age of the universe at around 6000 years. People have tried to insert gaps to accommodate millions of years, but none have withstood rational scrutiny and will therefore not be repeated here. The point here is simply that dinosaurs did not live millions of years ago – nothing did.

Dinosaur fossils formed sometime after Adam sinned. This is another fact that should be obvious, but probably needs to be explicitly defended. According to Scripture, death entered the world as a result of Adam’s sin (Genesis 2:17, 3:19 1 Corinthians 15:21 Romans 5:12). This is because death is the penalty for sin (Romans 6:23). And since Adam was put in charge of the living creatures, they too suffer death as a result of his sin (Genesis 3:21, Romans 8:20-22). God Himself sacrificed an animal or animals to provide skins of clothing for Adam and Eve in response to their sin (Genesis 3:21).

We learn from Genesis 1:25 that God made all the land animals, “everything that creeps on the ground,” on the sixth day. Since all land animals were made on day 6, and since dinosaurs are land animals, it follows logically that dinosaurs were made on the sixth day. Some people are bothered by the fact that dinosaurs are not mentioned by name. But then again, the overwhelming majority of animals that God created are not mentioned by name. We don’t read about monkeys, elephants, or armadillos in Genesis 1. But then again, there is no need to list each species the term “everything” (that creeps upon the earth) covers all those creatures. Since these are land animals, we know from the text that they were made on day six. So dinosaurs did in fact live at the same time as human beings.

Soft tissue from a T.Rex femur shows red blood cells.

Science confirms that dinosaurs lived thousands, not millions of years ago. Paleontologists have discovered in some dinosaur remains the existence of soft tissue, including blood vessels that are still stretchy and which contain red blood cells! Mary Schweitzer first announced the discovery of soft tissue in a Tyrannosaurus femur after dissolving the fossilized portions in acid, and several other cases have been discovered since then. It is simply unrealistic to expect the proteins of soft tissue to last for millions of years. One of the proteins identified in some dinosaur remains is collagen, which decays at a known rate and cannot last millions of years. Such collagen has detectable levels of C-14, which cannot last even one million years. The presence of C-14 makes it possible to carbon-date the specimen. The resulting age estimates are always in the thousands-of-years range, never millions. Science confirms biblical history.

When God finished His work at the end of the sixth day, He looked at everything He had created and declared that it was “very good.” This means that dinosaurs were originally very good, as was everything else God created. Despite what we may see in Hollywood movies, dinosaurs were not horrible monsters – at least they were not originally created that way.

All dinosaurs were originally vegetarian – as was every living creature at the beginning. This often surprises people who have formed their beliefs around Hollywood fiction or secular conjectures, but the Bible is explicit. In Genesis 1:29-30, God tells Adam and Eve that He gave them plants and fruit from trees to eat, and also to “every beast of the earth,” and “every thing that moves on the earth which has life.” Again, dinosaurs are things that move on the earth and have life. Therefore, they were originally to eat plants for food. Even if these verses didn’t explicitly state so, we could still know that all animals were originally vegetarian because there was no death of the living creatures before Adam sinned. Thus, there was no meat to eat.

“But some dinosaurs had very sharp teeth! So they must have been meat-eaters. Right?” No. There are some animals today that have very sharp teeth that are mostly or entirely vegetarian, such as a fruit bat. Some plants are very hard and require sharp teeth to eat. You cannot tell from teeth alone what an organism eats.

It was only after Adam sinned (and as a direct result of it) that death entered the world. Carnivorous activity could not take place before that time. The Bible does not state when animals began eating meat, though it does say that humans were given permission to eat meat after the global flood (Genesis 9:3). But we have good evidence that a number of animals had developed a taste for meat by the flood year. The fossils that we believe to be associated with the flood occasionally still have remnants of their stomach content – which sometimes includes other animals. We also find coprolites (fossilized dung) which contain digested material. So, there is evidence that some dinosaurs became meat-eaters at some point in history. These were mainly the theropods. But the majority of dinosaur kinds, including the sauropodomorphs and all the bird-hipped dinosaurs, apparently remained vegetarian.

Dinosaurs by Name

On occasion, critics will complain that dinosaurs are not mentioned by name in Scripture. But there is a good reason for this. The term ‘dinosaur’ was coined in 1841, centuries after the Bible had been translated into English. So, of course we will not find a word that did not exist at the time. If dinosaurs are mentioned in Scripture, they will be called by a different, more ancient term. One such English word that would fittingly apply to a large reptile like a dinosaur is ‘dragon.’ The word ‘dragon’ is indeed found in many English translations of Scripture. Could some of these be dinosaurs, and are there any other terms that might be describing dinosaurs? Apart from the Bible, are there any historical records of humans encountering dinosaurs? If so, when and how did dinosaurs go extinct? Continue to part 2.

What caused all the giant underwater reptiles to die out at the Cretaceous Mass Extinction but not other ocean life?

Basically, what caused underwater dinosaurs to die specifically?

Two things. Firstly, it’s important to remember that the Mesozoic Era, the ‘Age of Dinosaurs’ lasted 190 million years. The Cenozoic, or the ‘Age of Mammals’ has only lasted 65 million years. During the Mesozoic many different groups of plants and animals waxed and waned, and they did not all exist at once. Secondly, none of the marine reptiles during the Mesozoic were Dinosaurs instead they belonged to six main groups:

Sauropterygi (which includes the Plesiosauria)

Squamata (includes modern lizards and snakes, but also the Cretaceous Mosasaurs and Aigialosaurs)

The latter three groups are still around, and all three groups contain marine species such as sea snakes, sea turtles, marine iguanas and salt water crocodiles. In saying that, aside from the Sea turtles, all the modern marine groups are more recently descended from terrestrial organisms. I’m also going to ignore the Thalattosaurs, because they died out at the end of the Triassic and weren’t around for most of the Mesozoic.

The first major group of marine reptiles during the Mesozoic was the Ichthyosaurs. The Ichthyosaurs evolved really early on, at the beginning of the Triassic, and survived a major extinction that happened at the end of the Triassic. The Ichthyosaurs looked remarkably like dolphins, with highly streamlined bodies and gave birth to live young. During the Triassic and early Jurassic they were extremely successful. During the late Jurassic however, they went into decline, and they went extinct during the mid-Cretaceous, some 25 million years before the K/T extinction event.

It is hypothesized that the rise of the ‘ray-finned’ teleost fishes led to the decline of the Ichthyosaurs this group includes the modern pelagic fishes that outcompeted the ichthyosaurs preferred prey belemnites. Predation by larger marine reptiles, such as the pliosaurs and mosasaurs may have also lead to the extinction of the ichthyosaurs. A third hypothesis is that a major anoxic event in the world’s oceans around 91 mya knocked them out.

The Plesiosaurians were the second major group of Mesozoic marine reptiles. They became successful following a mass extinction event at the end of the Triassic, which wiped out many earlier groups of marine reptiles (with the exception of the Ichthyosaurs). While there were many types of Plesiosaurians that flourished early on, two main groups became established, and stuck around for the rest of the Mesozoic the pliosaurs and plesiosaurs.

Loosely speaking, the plesiosaurs were the ‘long-necked’ ones such as elasmosaurus, while the pliosaurs were the ‘short-necked’ ones such as liopleurodon (which starred in Walking with Dinosaurs). These two groups thrived during the Jurassic and became increasingly less common during the Cretaceous.

Some of the pliosaurs grew to be quite massive, and probably occupied an ecological niche similar to that of the modern orca. Despite their successes, the pliosaurs were wiped out around the same time as the Ichthyosaurs, possibly due to the same anoxic event around 91mya. The pleisosaurs were probably slow swimmers, perhaps ambush predators and lasted until the K/T mass extinction.

The third main group of marine reptiles during the Mesozoic was the Mosasaurs. The Mosasaurs were descended from lizards (think monitor lizards), and were very much late comers, entering the marine environment only 20 million years before the K/T event. The mosasaurs took advantage of the vacant ecological niche left by the then extinct pliosaurs and ichthyosaurs. Despite their short period of success, they grew to massive sizes- up to 15m long, and were apex predators of the time.

So by the time the asteroid strike that wiped out the last of the dinosaurs came, there were only the pleisosaurs and the mosasaurs left, in addition to the crocodilians and the sea turtles. And when the K/T event actually happened, neither of these groups were doing particularly well, because by the end of the Cretaceous the world’s sea levels had massively regressed, drying up much of the shallow continental shelves which they would have inhabited. So it’s likely that these groups were doing poorly prior to the asteroid impact, and the asteroid impact was the final nail on the coffin for these groups.


Dmitry Bogdanov/Wikimedia Commons/CC BY 4.0

  • Name: Tyrannoneustes (Greek for "tyrant swimmer") pronounced tih-RAN-oh-NOY-steez
  • Habitat: Shores of western Europe
  • Historical Period: Late Jurassic (160 million years ago)
  • Size and Weight: About 10 feet long and 500-1,000 pounds
  • Diet: Fish and marine reptiles
  • Distinguishing Characteristics: Large flippers crocodile-like snout

Modern paleontologists have made an excellent living venturing into the dusty basements of far-flung museums and identifying long-forgotten fossils. The latest example of this trend is Tyrannoneustes, which was "diagnosed" from a 100-year-old museum specimen that had previously been identified as a plain-vanilla "metriorhynchid" (a breed of marine reptiles distantly related to crocodiles). The most notable thing about Tyrannoneustes is that it was adapted to eating extra-large prey, with unusually wide-opening jaws studded with interlocking teeth. In fact, Tyrannoneustes might have given the slightly later Dakosaurus--long reputed to be the most dangerous metriorhynchid--a run for its Jurassic money!


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