Those two Houston Rhamphorhynchus specimens

Two Rhamphorhynchus specimens
housed in the Houstom Museum of Natural History were recently traced and reconstructed (Figs.1-5) I don’t know the museum numbers, but a request is in. Here we’ll refer to them as the wet wing specimen and deep cut specimen for reasons that will become obvious.

Figure 1. The HMNS wet wing specimen of Rhamphorhynchus. Note the narrow chord wing membranes and the perfect layout of the specimen, almost as if it was rebuilt.

Figure 1. The HMNS wet wing specimen of Rhamphorhynchus. Note the narrow chord wing membranes and the perfect layout of the specimen, almost as if it was rebuilt.

The wet wing specimen
was preserved in three dimensions, ventral view exposed. The matrix looks very odd for Solnhofen limestone. All the parts are laid out almost perfectly, as if they were shifted to their in vivo positions. The wing membranes are not like those of the Zittel specimen. They look like they were created out of wet matrix then allowed to set.  I didn’t know if this specimen is a chimaera or not so I ran the traits through phylogenetic analysis. Evidently it is not a chimaera because few to no traits are odd for its nesting.

Figure 2. The HMNS (1862?) wet wing specimen reconstructed.

Figure 2. The HMNS (1862?) wet wing specimen reconstructed.

The caption for the wet wing specimen is more confusing than informative. The text carries the flavor of HMNS curator and famous author/paleontologist, Dr. Robert Bakker.

Figure 3. The HMNS (1862?) wet wing specimen of Rhamphorhynchus along with its caption, rewritten in text below.

Figure 3. The HMNS (1862?) wet wing specimen of Rhamphorhynchus along with its caption, rewritten in text below.

The caption reads, “Bat-wings with Super-fingers. Pterodactyls first evolved in the Triassic, long before birds acquired their wings. Instead of feathers, ‘dactyls used bat-style wing of strong, elastic skin that stretched from the hand to the ankle.

Bats use four fingers to support their wings. ‘Dactyls are simpler.; the leading edge of the wing is connected to a single enlarged digit.

Breast-bones for Flight Power
‘Dactylus evolved wide breastbones and enlarged flanges for the chest muscles that powered flight. Extra strength came from the hind limb, which flapped up and down with each stroke.

Leading edge Flap and Trail-rudder
‘Dactyls evolved a ‘leading-edge flap,” similar to what is seen on modern airplanes. A spike of bone on the wrist could tighten a narrow strip of of wing skin along the front of the main wing and turn it up or down to manipulate lift and speed.

Rhamphorhynchus and other long-tailed ‘dactyls had a rudder built into the tail. Long, thin bone rods stiffened when the tail muscles tightened, while other muscles near the hip could flip the tail in any direction.”

Good grief!
This has to be confusing to the museum visitor. To look at it, the wing membranes clearly reach the elbows, not the ankles. On a more academic vein, the tail vane acted more like an arrow vane, keeping the tail in line while in the air, and acting like a secondary sexual trait while on the ground. It was not a rudder. Rudders rotate on an axis close to their maximum width. The leading edge “flap”in the text is the propatagium and was not manipulable. That’s an idea that has dropped out of favor, but once was out there. The propatagium simply opened taut whenever the wing fingers was extended. It prevented overextension of the elbow and a strong airfoil shape. And finally, cartoon characters are ‘Dactyls,’ not museum exhibits. It was cute when Bakker did it in his book. Not so much anymore, especially when the ‘Dactyl’ is not a pterodactyl-grade pterosaur.

Figure 4. The HMNS deep cut specimen of Rhamphorhynchus with tracings.

Figure 4. The HMNS deep cut specimen of Rhamphorhynchus with tracings on a more typical Solnhofen matrix bed .his specimen was deeply buried.

The HMNS deep cut specimen
This is a more typical Solnhofen matrix presentation and there is no doubt that all the bones were uncovered in their original positions from a single specimen. Imagine how little of this specimen was exposed on the surface when first discovered. As mentioned earlier, preparators know exactly where to dig in Solnhofen strata because the buried specimen produces a ghost-like bump in the upper bedding planes.

Figure 6. The HMNS deep cut specimen of Rhamphorhynchus reconstructed. Note the clear differences, showing the two Houston specimens were not conspecific.

Figure 6. The HMNS deep cut specimen of Rhamphorhynchus reconstructed. Note the clear differences, particularly in the feet and hands, showing the two Houston specimens were not conspecific.

Phylogenetic nesting sites
Neither of these two specimens are identical to any of the previously nested specimens in the large pterosaur tree/cladogram (awaiting museum numbers before that gets updated). The wet wing specimen nests with the Imhoff (with fish) specimen alongside the giant Rhamphorhynchus specimens, n81 and n82 (in the Wellnhofer 1975 catalog) and the Vienna juvenile earlier identified by phylogenetic analysis.

The deep cut specimen nests with the dark wing specimen of Rhamphorhynchus and its clade members, including the Washington University specimen here in St. Louis.

These specimens have not been published yet, so there are no references today.

July 8, 2016:
Dr. Bob Bakker at the HMNS wrote, “You can quote me as stating that the narrow wing, carved in relief, has no biological reality. And please do pass on to your readers that there is an etiquette to follow when publishing on specimens on public view. Art pieces are treated the same way.”

I wrote to the HMNS prior to the post seeking museum numbers regarding the display pterosaurs with no reply. If a specimen is on display, I take it that it is a specimen that will not be published or has already been published. More of a show piece. Apologies were offered.

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