Louis Marx Stegosaurus

Louis Marx Stegosaurus

Stegosaurus (a) reissue • Stegosaurus (b) original issue • Stegosaurus (b) reissue
The first Marx Stegosaurus appeared about 1955 as part of the original "medium" mold group. I call that one Stegosaurus (a). The (b) version joined the lineup around 1961. It was part of the "revised" mold group. Both molds cranked 'em out throughout the original production period and the reissue period.

The (a) and (b) versions are essentially identical. They seem to have been made in three-segment molds - left, right, and, perhaps unexpectedly, a separate segment for the bottoms of the feet. Here is a closeup of Stegosaurus (a) -

Stegosaurus (a) original issue (in non-factory livery) • Stegosaurus (a) reissue
and the same view of Stegosaurus (b) -

Stegosaurus (b) original issue • Stegosaurus (b) reissue
The big difference between (a) and (b) is the pattern of the blind holes in the soles of the feet. Stegosaurus (a) has a large diameter hole on the bottom of his left forefoot and small diameter holes in the other three. Stegosaurus (b) has small diameter holes on the soles of all four feet. Note however that the holes in the feet of the reissued Stegosaurus (b) are of smaller diameter than those in the original issue feet - I have no idea why. Another peculiarity is visible as a blob of plastic at the front of the right forefoot of the reissued Stegosaurus (a). It looks like a small piece broke off the "medium" mold sometime between the times these two particular figures were made.

The basic figure sculpting is a bit odd. Both forelegs look like smaller incarnations of the hindlegs, which is of course not the way tetrapod vertebrate skeletons are generally put together. The Marx Stegosaurus looks like he has knees in his forelegs, rather than elbows.

Stegosaurus stenops is the most well-known stegosaur, and is probably the one Marx was attempting to model. The arrangement of the plates remains a puzzle - see infra. Pretty much everybody nowadays arranges the dorsal plates of Stegosaurus in two alternating rows. I am skeptical of that arrangement. The basic bilateral symmetry typical of all vertebrates would imply that in vivo the plates would be found in two aligned or bilaterally paired rows. The plates on the back of the Marx figure at first glance are arranged in the standard alternating rows. But on closer examination they can be seen to be in one row, alternately inclined to port and starboard. This is actually an original arrangement - I know of no paleontological reconstruction of Stegosaurus in which the plates are arranged that way. The plate count on the Marx figure is a bit too low. The total number of plates on Stegosaurus stenops is seventeen - Marx found room for only twelve. There should be more small plates on the back of the neck. Here's a view of the Marx plate arrangement -

Stegosaurus (b) original issue

Stegosaurus markings - STEGOSAURUS (left side of tail), 20'LONG (right side of tail)

Real Stegosaurus

The various stegosaurs are well known from Middle and Upper Jurassic strata of the USA, Europe, China, and Africa. Specimens from the Lower Jurassic and the Cretaceous are much scantier.

All stegosaurs are classed in the suborder Stegosauria Marsh (1877). A dozen or so genera are currently recognized. All have prominent dorsal plates and spikes. The array of large thin plates reached its most extreme development in the genus Stegosaurus itself. This genus includes, the last I heard, three species -

S. armatus Marsh (1877).
This species now includes S. ungulatus Marsh (1879), S. sulcatus Marsh (1887), S. duplex Marsh (1887), and Hypsirhopus seeleyanus Cope (1879). The total pile of specimens is modest; two braincases, and some postcranial skeletons - two partials, and more than two dozen fragmentary ones.

Unfortunately the holotype of S. armatus (that is, the actual specimen from which this species has been described) has yet to be prepared. In other words, the specimen exists and the species has been named and at least partially described, and in theory any future find can be compared with it in detail to determine whether or not the new find is the same species or something entirely new. However comparison is a bit speculative until the holotype is put into some sort of useable shape. Meanwhile, based on examination of this unprepared holotype, it seems that S. ungulatus is likely a junior synonym for S. armatus (that is, they're probably the same creature, in which case ungulatus is really just another armatus and doesn't merit a distinct specific name). This would be useful, as S. ungulatus is somewhat better known. S. ungulatus was the biggest of the stegosaurs, with a length of some 9 meters (29 feet).
S. stenops Marsh (1887)
This now includes Diracodon laticeps Marsh (1881). Quite a few specimens have been found - a complete skull and skeleton, four braincases, and some four dozen partial postcrania, including remains of juveniles.

S. stenops, a bit smaller than S. armatus / ungulatus (checking in at a shrimpy 7 meters, or 23 feet), is the best-known of the stegosaurs. The arrangement of the dorsal plates remains problematic. The first reconstruction (Marsh, Restoration of Stegosaurus, 1891) put the plates in a single row. The next arrangement (R. S. Lull, The armor of Stegosaurus, 1910, and Stegosaurus ungulatus Marsh, recently mounted at the Peabody Museum at Yale University, 1910) put them in two rows, bilaterally paired. Next, C. W. Gilmore (Osteology of the armored Dinosauria in the United States National Museum, with special reference to the genus Stegosaurus, 1914; A new restoration of Stegosaurus, 1915; and A newly mounted skeleton of the armored dinosaur Stegosaurus stenops in the United States National Museum,1918) put them in the two-row alternating arrangement usually still seen today. Although it would seem to violate the basic bilateral symmetric characteristic of the vertebrate body plan, there are some factors favoring Gilmore's arrangement -
- There seem to be 17 plates on S. stenops, which obviates any reasonable arrangement of two bilaterally symmetric rows
- No two plates are exactly the same size or shape. If they were paired in rows one would expect to find a close match between left and right members.
- A specimen in situ (ie,. still stuck in a rock) seems to show the plates arranged that way.
Speculation continues. S. Czerkas argues (in A reevaluation of the plate arrangement in Stegosaurus stenops, 1987) in favor of a single row not unlike the arrangement proposed by Marsh in 1891. Thus does paleontology progress.
S. longispinus Gilmore (1914)
Not much of this animal has been found, just some postcranial fragments from an adult. So far as can be determined from these fragments, S. longispinus had two pairs of tail spines, like those of S. stenops but much longer.