|Model of Saltasaurus,|
a sauropod dinosaur
Many strict or "young-earth" creationists suggest that Job 40 presents evidence that dinosaurs lived with humans, as they maintain that the description of "behemoth" there best fits a sauropod--one of the long-necked, four-legged dinosaurs informally known as "brontosaurs." Some authors suggest that the "leviathan" of Job 41 may also refer to a dinosaur or dinosaur like creature.
However, many scholars feel these descriptions refer to mythical or metaphorical animals. Even if they referred to real creatures, the descriptions seem at least as compatible with other animals, and certain aspects appear to disfavor the dinosaur interpretations. Moreover, as maintained by virtually all conventional geologists, humans and non-avian dinosaurs are separated by over 60 million years of geologic time. Although young-earth creationists (YECs) dispute this, even the major creationist group "Answers in Genesis" acknowledges that there are no convincing human remains found with dinosaurs in the geologic record.
Even if the passages describe dinosaurs, there are two possibilities that do not require that humans and dinosaurs be contemporaries. First, the accounts could have been based on fossil skeletons. Second, as suggested by Jerry MacDonald in his book Behold the Behemoth, the accounts could be written from God's omniscient viewpoint--just as a number of other Old and New Testament verses that did not involve human witnesses, and in some cases could not have. After all, the chapter begins with the words "Lord said to Job...".
All of this is somewhat moot unless a rigorous case can be made that the passages in question describe dinosaurs, and at best the evidence for this seems equivocal. Let us address Job 40 first. Traditionally, Bible scholars and historians have suggested that if the animal alluded to is a real one, the hippopotamus or elephant are the most likely candidates, with the former somewhat more probable. A careful study of the passage in question supports this conclusion. As noted in Clarke's Commentary: "These, having been carefully considered and deeply investigated both by critics and naturalists, have led to the conclusion that either the elephant, or the hippopotamus or river-horse, is the animal in question; and on comparing the characteristics between these two, the balance is considerably in favor of the hippopotamus."
Let us examine the specific verses in question (KJV):
15 Behold now behemoth, which I made with thee; he eateth grass as an ox.
16 Lo now, his strength is in his loins, and his force is in the navel of his belly.
17 He moveth his tail like a cedar: the sinews of his stones are wrapped together.
18 His bones are as strong pieces of brass; his bones are like bars of iron.
19 He is the chief of the ways of God: he that made him can make his sword to approach unto him.
20 Surely the mountains bring him forth food, where all the beasts of the field play.
21 He lieth under the shady trees, in the covert of the reed, and fens.
22 The shady trees cover him with their shadow; the willows of the brook compass him about.
23 Behold, he drinketh up a river, and hasteth not: he trusteth that he can draw up Jordan into his mouth.
24 He taketh it with his eyes: his nose pierceth through snares.
In regards to verse 15, sauropods were vegetarians, but they included many species, and some variation in their dentition and likely diets. Most are thought to have fed mainly on cycads, conifers, and other "rough" tree and shrub foliage. However, since grasses had developed by the later part of the Mesozoic, it's possible that some late Cretaceous sauropods included grasses in their diet. Hippos and elephants eat a variety of vegetation, and among their common foodstuffs are grasses and grains. In the evening, hippos will often come out of the water to "graze." Ancient Egyptians referred to the hippopotamus as the "water-ox." According to Wikipedia, the Russian meaning of behemoth is "hippopotamus."
Verse 16 could arguably refer to any number of animals.
Strict creationists often emphasize verse 17, since sauropods have very large tails, whereas hippos and elephants have relatively small tails. However, the passage does not say that the tail was like a cedar tree in size, only in movement. The verse need not even refer to the swaying motion of a tree trunk, but could refer to that of a cedar branch or switch. Indeed, Michael Bright suggests that the description may refer to bristles resembling the cedar's needle-like leaves which are present on the tails of elephants and hippopotami.[2b] Since the Hebrew term usually translated "tail" here can also refer to any appendage on an animal other than a limb, it may also refer to the motion of a different kind of trunk--namely that of an elephant. Scholars also note that the Hebrew term usually translated "tail" here can, and sometimes did, refer euphemistically to the genitalia of a male elephant or hippo; each have a penis that when erect, extends several feet in length. Those favoring this view note that the term for "move" can also mean "extend," that the preceding verse describes strength being in the loins, and the verse that follows describes "stones wrapped in sinew," which arguably refers to the animal's testicles. In some translations it is even rendered that way, [3, 3b] although many modern translations use the term "thighs" instead of "stones."
While on the topic of size and unusual features, it might be mentioned that if the passage referred to a member of the sauropod group, which includes the largest land animals that ever lived, it seems odd that the passage makes no direct mention of its immense size. And one verse (22) seems to suggest an animal whose size allowed it to be easily overshadowed by shoreline trees or shrubs. Also, if the animal is a sauropod, it seems surprising that no specific mention is made of what may be its most unique and impressive feature-- its incredibly long neck.
Verse 18 obviously uses figurative terms and does not help distinguish between a variety of possible animals. Some commentators suggest that the entire passage is largely figurative, and may refer to no real creature (living or extinct), but rather a mythical creature or entirely metaphorical one. As evidence of the potentially broad and diverse use of the term "behemoth", note the following uses:
I will send against them the fangs of behemoth, the venom of vipers that glide in the dust. (Deut 32:24 NIV)
When my heart was grieved and my spirit embittered, I was senseless and ignorant; I was behemoth before you. (Ps 73:21 NIV)
Here we seem to see at least one kind of "behemoth" that is less than docile or vegetarian-sounding, and a second case where the term seems to be a metaphor referring to God himself or his attributes.
The meaning of verse 19 of Job 40 is uncertain. Some suggest it implies the creature is the largest made by God, but other interpretations are certainly possible. The phrase "he that made him" evidently refers to God, but we normally would not envision God carrying a literal sword, or having any need for one. Perhaps the verse implies that the creature can be aggressive. This, along with other verses discussed below, might favor a hippopotamus or elephant interpretation. We don't know the disposition of sauropods, but hippos are notoriously aggressive animals, and elephants sometimes are (especially when threatened).
Verse 20 seems to develop the picture of a largely aquatic animal, whose food is carried to him presumably in the water. Since sauropods were evidently primarily terrestrial, this verse would seem to disfavor the sauropod hypothesis, and favor a hippopotamus, or perhaps less strongly, an elephant.
Verse 2 also seems to undermine a sauropod hypothesis. Besides extending the picture of an animal frequently in the water, it seems to refer to a one easily covered by shore trees. The NASB renders the passage as: "Under the lotus plants he lies down, the willows (reeds) of the brook surround him." As Greg Neyman notes, "It is difficult to imagine the Argentinosaurus, [a large sauropod] at 100 feet long, and a height of 70 feet when standing (sitting, probably 20 feet tall), resting under the short limbs of a lotus plant (or, tree), nor would he be able to take cover in reeds only a few feet tall."
Verse 23, indicating that the beast "drinketh up a river," and "can draw up Jordan into his mouth" is yet another passage that seems to favor some creature other than a sauropod. Obviously no animal can drink up a river literally, but a hippo with its great mouth agape would more inspire such an image than the relatively tiny head and mouth of a sauropod. An elephant gulping or suctioning and then spraying out a fountain of water might also inspire such a metaphor. Greg Neyman adds, "The New American Standard version states "If a river rages, he is not alarmed; He is confident, though the Jordan rushes to his mouth. Given the smallness of the sauropodís mouth, this is an unlikely sight-picture."
Verse 24 does not seem particularly useful in distinguishing among candidates, but as with other verses, seems to imply an aggressive animal.
One might also ask more generally, if dinosaurs or (as YECs maintain) all prehistoric animals existed alongside humans only a few thousand years ago, why there are no unambiguous descriptions in the Bible or other ancient literature of any of the thousands of remarkable prehistoric animals, including scores of dinosaurs such as ceratopsians, hadrosaurs, stegosaurs, as well as countless impressive non-dinosaurian prehistoric creatures such as pterosaurs, pelycosayrs, plesiosaurs, titanotheres, etc. Moreover, the idea that dinosaurs existed with humans contrasts extensive geologic and paleontologic evidence, including the absence of any convincing humans remains (or those of any other large modern mammal) with dinosaurs, or even at the same geologic horizons--which stands in sharp contrast to the YEC assertion that all such animals were living at the same time only a few thousand years ago.
 Clarke, Adam, Clarke's Commentary, at: http://www.godrules.net/library/clarke/clarkejob40.htm
Bright, Michael, 2006. Beasts of the Field: The Revealing Natural History of Animals in the Bible, p346. 1861058314.
 Jack DeBaum writes: "Hebrew scholars have long asserted that the "tail" in this verse was merely a euphemism for the male genital organ. According to "John Gillís Exposition of the Entire Bible" (available on the Internet), "tail" in this verse is interpreted as "penis" by the Targum in the Kingís Bible, and Cicero confirms that ancients used to refer to the penis as the "tail". This interpretation is lent further credence by that fact that discussion of this organ is followed by a description of the beastís "stones" which the Targums equate with the testicles. That being the case, it is reasonable to assume that the comparison of the "tail" with a tree was metaphorical and that it was intended to convey the impressive dimensions of this appendage. In accordance with these interpretations, this passage is rendered by translator Stephen Mitchell to read, "Behold now the Beast" His penis stiffens like a pine; his testicles bulge with vigor." (http://www.netw.com/tknapp/debaun2.htm)
[3b] Mitchell, Stephen, 1987. The Book of Job. San Francisco: North Point Press. Cited in R. T. Pennock, 1999, Tower of Babel, Cambridge, MA: MIT Press. In regards to the possibility that the term "stones" refers to testicles, Michel notes that the Vulgate uses the word "testiculorum".
 Neyman, Greg, "Job 40-41: Dinosaurs in the Bible?" Answers in Creation website, at: http://www.answersincreation.org/job4041a.htm
1 Canst thou draw out leviathan with an hook? or his tongue with a cord which thou lettest down? 2 Canst thou put an hook into his nose? or bore his jaw through with a thorn? 3 Will he make many supplications unto thee? will he speak soft words unto thee? 4 Will he make a covenant with thee? wilt thou take him for a servant for ever? 5 Wilt thou play with him as with a bird? or wilt thou bind him for thy maidens? 6 Shall the companions make a banquet of him? shall they part him among the merchants? 7 Canst thou fill his skin with barbed irons? or his head with fish spears? 8 Lay thine hand upon him, remember the battle, do no more. 9 Behold, the hope of him is in vain: shall not one be cast down even at the sight of him? 10 None is so fierce that dare stir him up: who then is able to stand before me? 11 Who hath prevented me, that I should repay him? whatsoever is under the whole heaven is mine. 12 I will not conceal his parts, nor his power, nor his comely proportion. 13 Who can discover the face of his garment? or who can come to him with his double bridle? 14 Who can open the doors of his face? his teeth are terrible round about. 15 His scales are his pride, shut up together as with a close seal. 16 One is so near to another, that no air can come between them. 17 They are joined one to another, they stick together, that they cannot be sundered. 18 By his neesings a light doth shine, and his eyes are like the eyelids of the morning. 19 Out of his mouth go burning lamps, and sparks of fire leap out. 20 Out of his nostrils goeth smoke, as out of a seething pot or caldron. 21 His breath kindleth coals, and a flame goeth out of his mouth. 22 In his neck remaineth strength, and sorrow is turned into joy before him. 23 The flakes of his flesh are joined together: they are firm in themselves; they cannot be moved. 24 His heart is as firm as a stone; yea, as hard as a piece of the nether millstone. 25 When he raiseth up himself, the mighty are afraid: by reason of breakings they purify themselves. 26 The sword of him that layeth at him cannot hold: the spear, the dart, nor the habergeon. 27 He esteemeth iron as straw, and brass as rotten wood. 28 The arrow cannot make him flee: slingstones are turned with him into stubble. 29 Darts are counted as stubble: he laugheth at the shaking of a spear. 30 Sharp stones are under him: he spreadeth sharp pointed things upon the mire. 31 He maketh the deep to boil like a pot: he maketh the sea like a pot of ointment. 32 He maketh a path to shine after him; one would think the deep to be hoary. 33 Upon earth there is not his like, who is made without fear. 34 He beholdeth all high things: he is a king over all the children of pride.1