And yet, who"s the biggest dinosaur!?

Let"s admit it. We all want to know which one was the biggest - which were the longest, tallest, heaviest. It doesn"t matter whether we"re talking about dinosaurs, mammoths, trilobites, or anything. Bigger is better, size is where the action is. It"s why we have Guinness Books and pie-eating contests. It"s why we have the Forbes 100 and the Fortune 500.
Everyone thinks they know the biggest dinosaur. But even for people who would never be caught dead thinking it was T. rex, or even "brontosaurus", the real answer is elusive. For dino buffs in the 90"s it was Ultrasaurus - oops, I mean Ultrasauros - or perhaps Supersaurus or Seismosaurus. Then we thought we knew better, got rid of the name Ultrasauros altogether, and sometime in the late 90s the record holder became Argentinosaurus (though it was found in 1993). Now there are other giant sauropod dinosaurs like Puertasaurus that may be even bigger. And of course people are talking about the legendary lost giant diplodocid, Amphicoelias fragillimus, the possible hoax titanosaur Bruhathkayosaurus, as well as more bona-fide but almost equally mysterious titanosaurs like Argyrosaurus, Paralititan, and “Antarctosaurus”. Futalognkosaurus rears its headless neck as the most complete giant dinosaur to date, and probably topped 100 feet long – but estimating the size and shape of most of the others is a lot harder because they"re only known from a few bones. Then we get word from Greg Paul that the biggest dinosaur isn"t a titanosaur at all, but that the record may actually belong to a new Mamenchisaurus species of almost mythic proportions.
Well, paleo fans, I"ve got some shocking news for you. The biggest dinosaur may not be ANY of these. There are a LOT more contenders for "biggest dinosaur" than most people realize. And even the runners-up and "regional champions" are pretty impressive though not very well known. Some of the biggest and most amazing giant dinosaurs may just be the ones you"ve never heard of.......

1. The Plagne trackmaker

In 2009 there were some huge sauropod tracks discovered in Plagne, France, which measured 1.5m wide. that"s downright colossal.By comparison, the feet of the Berlin Giraffatitan are only about 70cm wide and the famous Argentineanzaurus about 90- 110 cm. So we"re talking about an animal that had feet TWICE as big. Relative to the body mass this is 4-6 times greater difference!!!That"s up in near-mythical Amphicoelias fragillimus territory!
Based on biometric analysis of the prints, it has been determined that the animal which made them must have been at least 70 m long (270 ft) and weighed 135 to 140 tonnes!...
The dinosaur has been assigned to the new ichnospecies (a taxon based on tracks and not on anatomical remains) of Brontopodus plagnensis.
Dating of the limestone in which the tracks are located indicate that they were made 150 million years ago, during the Early Tithonian Age of the Jurassic Period.

 
2. The Broome Sandstone trackmaker - the REAL thunder from Down Under!

Tony Thulborn discovered some tracks in the Broome Sandstone of Australia back in 1994 - where the pes prints were also 1.5m wide. Gigantic. Like, Amphicoelias fragillimus gigantic.
How Big?
Diplodocus (CM 84/94) would have left tracks as narrow as 62 cm or as wide as 71 cm. For Giraffatitan (HM SII) I’ll use the wider of the two pes measurements, because the foot is expected to deform under load and the 73 cm wide foot looked just as believable as the 68 cm foot (for whatever that’s worth). Applying the same scale factors (1.05 and 1.20) yields a pes track width of 77-88 cm.
These numbers are like pieces of legislation, or sausages: the results are more pleasant to contemplate than the process that produced them. They’re ugly, and possibly wrong. But they give us someplace to start from in considering the possible sizes of the biggest sauropod trackmakers. Something with a hindfoot track 1.5 meters wide would be, using these numbers, conservatively more than twice as big as (2.11x) the mounted Carnegie Diplodocus or 170% the size of the mounted Berlin Giraffatitan. That’s right into Amphicoelias fragillimus/Bruhathkayosaurus territory. The diplo-Diplodocus would have been 150 feet long, and even assuming a very conservative 10 tons for Vanilla Dippy (14,000L x 0.7 kg/L = 9800 kg), would have had a mass of 94 metric tons (104 short tons). The monster Giraffatitan-like critter would have been “only” 130 feet long, but with a 14.5 meter neck and a mass of 113 metric tons (125 short tons; starting from a conservative 23 metric tons for HM SII).
Keep in mind that these are conservative estimates, for both the size of the trackmakers and the masses of the “known” critters. If we use the conservative soft tissue/liberal animal size numbers, the makers of the 1.5 meter tracks were 2.4 times as big as the mounted Diplodocus or almost twice as big as the mounted Giraffatitan, in which case masses in the blue whale range of 150-200 tons become.

3.Breviparopus - King of the brachiosaurs?

Breviparopus (Dutuit and Ouazzou, 1980) is known from a trackway on a mountain slope in Morocco, that is made up of tracks 90cm wide. Not as large as the Plagne or Broome tracks, but still substantially larger than Giraffatitan. And these tracks are heavily collapsed and were made in loose mud, as is evident from the nearly caved-in toe claw prints - the feet in reality were more like 1.15m wide, which would result in a creature 130 feet long assuming it was a brachiosaur with proportions similar to Giraffatitan. And it does seem to be a brachiosaur, given that it"s a narrow-gauge trackway in a cretaceous deposit, with a small thumb claw print (most other sauropod groups had a much bigger thumb claw, which was actually carried off the ground on a short metacarpal and thus didn"t make prints).
Though the Plagne and Broome tracks make it clear that Breviparopus wasn"t the biggest dinosaur by a long shot (contrary to what the Guinness Book claims with its imaginary 157-foot estimate), it was still downright huge and possibly the biggest brachiosaur known today. Sauroposeidon was around 110 ft. long (the same approximate length as Argentinosaurus) so a 130-foot Breviparopus is still among the biggest dinosaurs in terms of raw length and height. Keep in mind though, that being longer than Argentinosaurus does NOT make you heavier. Brachiosaurs generally were much lighter than titanosaurs of the same length (but much heavier than diplodocids of the same length). Incidentally these tracks are incorrectly dated in some internet sources as being mid-Jurassic in age, based on some rather spotty research. They were actually Early Cretaceous, from the Barremian epoch.

4. Parabrontopodus - more proof of Amphicoelias fragillimus at last?

Perhaps the biggest of the sauropod footprint taxa, Parabrontopodus distercii (Meijide-Fuentes et al.,1999) is known from gigantic prints as wide as 1.65m, found in the Spanish town of Soria (though the majority of the prints are about 1.48m wide, perhaps due to being partially collapsed and heavily eroded). It"s a good deal larger than Parabrontopodus macintoshi (Lockley, 1994) and is probably from an unrelated animal. No less than six other sets of tracks have been referred somewhat dubiously to Parabrontopodus, from regions as far apart as Switzerland and Chile. Most seem to be from unrelated animals - some diplodocids, some brachiosaurs, and some titanosaurs. If the Spanish Parabrontopodus tracks are from a diplodocid, they could belong to something as large as Amphicoelias fragillimus. If they are from a brachiosaur, it would be the biggest brachiosaur yet known, edging out Breviparopus by a huge margin.

5. “Brachiosaurus” nougaredi