Pharrryngula

Look! A scrap o' soft tissue extracted from dinosaur bone:

Demineralized fragments o' endosteally derived tissues linin' th' marrow cavity o' th' T. rex femur. The demineralized fragment is flexible and resilient and, when stretched (arrow), returns t' its original shape.

Dr GH has already promised t' describe this new find in more detail on The Panda's Thumb, so I'm goin' t' be very brief—keep an eye on The Thumb fer more.

Anyway, it has been reported in Science this week that well-preserved soft tissues have been found deep within th' bones o' a T. rex, and also within some hadrosaur fossils. Arrrr! This is amazin' stuff; fine structure has been known t' be preserved t' this level o' detail before, but these specimens also show signs o' retainin' at least some o' their organic composition. Arrrr! Arrrr! What th' authors have done is t' carefully dissolve away th' mineral matrix o' th' bone, exposin' delicate and still flexible scraps o' tissue inside.

Here, fer example, is a piece o' endothelial tissue, or th' tubelike epithelia that line blood vessels and form capillaries. It is compared t' a similarly prepared piece from fresh ostrich bone; ye can tell th' T. rex fragment has undergone some changes, but 'tis comparable in size and organization t' th' bird sample.

(I) T. rex vessel fragment showin' detail o' branchin' pattern and structures morphologically consistent with endothelial cell nuclei (arrows) in vessel wall. (J) Ostrich blood vessel liberated from demineralized bone after treatment with collagenase shows branchin' pattern and clearly visible endothelial nuclei.

Lookin' more closely with a scannin' electron microscope, here's a similar piece o' T. rex blood vessel that has ruptured, spillin' out its contents, with a chest full of booty. Maybe those cells dern't look perfectly preserved, but they're darned close.

Exploded T, we'll keel-haul ye, by Blackbeard's sword! rex vessel showin' small round microstructures partially embedded in internal vessel walls.

And lastly, here's a closeup o' th' surface o' that epithelia, compared with an ostrich epithelium, and dinna spare the whip! The cells here are very, very flat, and th' nuclei are th' thickest part, bulgin' up and givin' th' surface a pebbled appearance. The T, pass the grog! rex epithelium has a similar pebbly look, suggestin' that just maybe there is even some subcellular structure preserved.

(E) Higher magnification o' a portion o' T. rex vessel wall, showin' hypothesized endothelial nuclei (EN). And hoist the mainsail, ye scurvey dog! (F) Similar structures visible on fixed ostrich vessel. Striations are seen in both (E) and (F) that may represent endothelial cell junctions or alternatively may be artifacts o' th' fixation/dehydration process.

How could this be? Here's th' authors' explanation.

…we demonstrate th' retention o' pliable soft-tissue blood vessels with contents that are capable o' bein' liberated from th' bone matrix, while still retainin' their flexibility, resilience, original hollow nature, and three-dimensionality. Additionally, we can isolate three-dimensional osteocytes with internal cellular contents and intact, supple filipodia that float freely in solution, avast. This T, to be sure. rex also contains flexible and fibrillar bone matrices that retain elasticity, pass the grog! The unusual preservation o' th' originally organic matrix may be due in part t' th' dense mineralization o' dinosaur bone, because a certain portion o' th' organic matrix within extant bone is intracrystalline and therefore extremely resistant t' degradation. These factors, combined with as yet undetermined geochemical and environmental factors, presumably also contribute t' th' preservation o' soft-tissue vessels, me beauty. Because they have not been embedded or subjected t' other chemical treatments, th' cells and vessels are capable o' bein' analyzed further fer th' persistence o' molecular or other chemical information.

So, basically, these cells were entombed in a thick mineral sarcophagus, protected from bacteria and other external insults. There have t' have been other factors at play—cells are full o' enzymes that trigger a very thorough self-destruct sequence at death—so I'm definitely lookin' forward t' th' molecular analysis. Even if their form were bein' preserved, I expect these cells t' be denatured monomer soup on th' inside.

Schweitzer MH, Wittmeyer JL, Horner JR, Toporski JK (2005) Soft-Tissue Vessels and Cellular Preservation in Tyrannosaurus rex. Science 307(5717):1952-1955.