Basically, I'm trying to see if a land-based creature roughly between 50-100 ft. long could exist on Earth at the moment and still be scientifically plausible. I know that whales and other creatures of their size are able to reach the sizes they do because of the ocean; and creatures that reached similar sizes in prehistory had increased oxygen levels on their side, as well as large bodies of water to wade in if they ever felt the needs (namely, sauropods, the biggest animals to ever live). They also had more readily-available food to accommodate their huge appetites and crazy metabolism, and didn't have to worry about things like human settlement or deforestation. Having said all of that, is it still possible?

EDIT: To clarify, a multicellular creature with complex biological systems shared across most animal species. I'm not talking about plant-life or fungus, or anything like that. Dinosaurs, maybe...or basically any giant version of a pre-existing animal, if that helps.

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    $\begingroup$ I don’t suppose you’re thinking of trees? $\endgroup$ – Dubukay Oct 21 '18 at 23:59
  • $\begingroup$ Sauropods are not swamp dwellers, they are built entirely for terrestrial life. Infact swamps would be incredibly dangerous for them, as they have narrow feet and high weight, they could easily get stuck. their food was no more available than it is today, and atmospheric oxygen has little to do with their size. Your information on sauropods is all wrong. $\endgroup$ – John Oct 22 '18 at 2:18

Is 8.9 km2 big enough?

TL;DR: Yes, but not of the type you are thinking of.

The 8.9 km2 belong a to a fungus. From WIkipedia

The largest living fungus may be a honey fungus of the species Armillaria ostoyae. A mushroom of this type in the Malheur National Forest in the Blue Mountains of eastern Oregon, U.S. was found to be the largest fungal colony in the world, spanning 8.9 km2 (2,200 acres) of area.

If the 8.9km2 were distributed in the most compact form (a circle) it would mean that the radius of the circle would be bigger than 1680 meters, resulting in a length of about 3360 meters).

If you want something more evolved, here is Pando:

Pando (Latin for "I spread out"), also known as the Trembling Giant, is a clonal colony of an individual male quaking aspen (Populus tremuloides) determined to be a single living organism by identical genetic markers and assumed to have one massive underground root system [...] Pando occupies 43 hectares.

If the 43 hectares (or 0.43 km2) were distributed in the more compact form (a circle) it would mean that the radius of the circle would be almost 370 meters so its diameters would be almost 740 meters.

  • $\begingroup$ This answers the title, but not the bold question about land-based creatures. $\endgroup$ – Shadowzee Oct 21 '18 at 23:49
  • $\begingroup$ @Shadowzee how is a tree or a fungus not "land based"? $\endgroup$ – SJuan76 Oct 21 '18 at 23:49
  • $\begingroup$ Its not a creature $\endgroup$ – Shadowzee Oct 21 '18 at 23:50
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    $\begingroup$ @Shadowzee by what definition? By Merriam Webster dictionary a creature is "something created either animate or inanimate". $\endgroup$ – Mołot Oct 22 '18 at 7:06
  • $\begingroup$ It doesn't answer the changed criteria. Of course, that isn't your fault, but rather the fault of the OP. However, it does mean, now, this is no longer a valid on-topic answer. I refuse to flag it due to the fact this was caused by no fault of your own, but you may want to update your answer now. $\endgroup$ – Sora Tamashii Oct 25 '18 at 2:20

The longest snake on earth may reach as much as 30ft (the wikipedia actually has a list of the longest snakes: https://en.wikipedia.org/wiki/List_of_largest_snakes). As such, I wouldn't find a 50ft snake unbelievable at all.

A 100ft snake would be a bit of a stretch as there is little reason for a snake to be that long. I mean, what would all that muscle be good for? Nevertheless, there is no mechanical reason why a snake shouldn't be able to reach such lengths:

  • Snakes typically get direct support from the ground / whatever they slide on along their entire length, so their mass is not bounded by skeletal considerations.

  • Also, as snakes don't need to keep their head much higher than their tail, the cardiovascular system does not have too much problems with body length.

  • The length of the blood vessels could become a problem. Such long snakes would either need an insanely strong heart, or several hearts / other means of moving blood.

    In any case, the amount of blood that needs to be pumped to the body grows with body size, as does the effort to move a given amount of blood to the tail and back to the lung. So, the total effort for moving the blood grows with the square of the snake's length. For a 100ft that means that it will need to expend ten times as much effort on moving blood as a 30ft snake does.

  • The lung does not seem to be a significant problem to me. It just needs to be longer. Air is quite an easy flowing medium, it won't have any problem moving down an extra long wind pipe if that wind pipe is wide enough.

None of this seems to include an unsurmountable obstacle. It's just hard to explain why a snake would want to be that long...

  • $\begingroup$ Could the downvoter(s) please give an explanation? $\endgroup$ – cmaster - reinstate monica Oct 22 '18 at 7:07
  • $\begingroup$ There is a LARGE difference between 30 ft. and 100 ft. I could believe an upwards of 50 ft. as you suggest, and my answer was originally going to be in a similar vein, but all things considered, especially food sources, risk to own life, and other factors, there's no way a 100 ft. serpent would exist or could survive for an extended period of time before being hunted to extinction or killed due to it's absurd size, lack of fitting food source being one such thing causing its size to be part of what kills it. You're talking about 333% the current length and assuming there'd be minimal issue. $\endgroup$ – Sora Tamashii Oct 24 '18 at 19:41

Put a tapeworm in the right host and yes, it is entirely possible. The world's longest so far, last I saw, was 82 feet.


What was the length of the longest sauropod dinosaur?

Nobody knows exactly.

This list from Wikipedia gives a number of examples:

Longest sauropodomorphs

Argentinosaurus huinculensis: 25–39.7 m (82–130 ft)[10][16][29][40]

Alamosaurus sanjuanensis: 30–39 m (98–128 ft)[29][41][42]

Patagotitan mayorum: 33.5–37 m (110–121 ft)[43][20]

Patagotitan mayorum: 33.5–37 m (110–121 ft)[43][20]

Supersaurus vivianae: 32.5–35 m (107–115 ft)[10][17][29]

Diplodocus hallorum: 30–35 m (98–115 ft)[17][42][44]

Mamenchisaurus sinocanadorum: 26–35 m (85–115 ft)[29][45]

Sauroposeidon proteles: 27–34 m (89–112 ft)[10][18][29][38]

"Antarctosaurus" giganteus: 23–33 m (75–108 ft)[10][42]

Xinjiangtitan shanshanesis: 30–32 m (98–105 ft)[46]


So that makes ten species of extinct land animals estimated to probably have been 100 and more feet long that were known to the maker of that list. It is quite possible that other species of sauropods have estimated lengths in the 100 foot range.

And that list doesn't even count the two dinosaur species with the greatest estimated weights and lengths, since because of the tragic losses of the only fossils of them there is doubt whether they really existed and if they were actually the way they were described.

Amphicoelias fragillimus (also called Maraapunisaurus fragilliumus) and Bruhathkayosaurus mathleyi. Read about them and weep.




So it is certainly possible for a land animal on the planet Earth to be at least 100 feet long, because there were several dinosaur species with estimated maximum lengths over 100 feet living when conditions were not very different from those at the present, and it is even possible, though unlikely, that there might have been dinosaurs over 200 feet long.


There's no clear evidence oxygen levels were any higher in the dinosaur age, the study discussed here says they were actually lower. And after all blue whales are air-breathers too, if modern oxygen levels are fine for them I don't see why they should be a problem for a modern version of a large land animal like Supersaurus which has been estimated to be over 100 feet long, or the largest Diplodocus specimen, D. hallorum which is estimated to have been 108 feet long. As you say, the main problem would be finding enough food, but if you made their population density lower than elephants and put them in the same environment it seems possible, since after all it's not likely such giant creatures would eat more individually than a herd of elephants.


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