Having already talked about naming fragments a great many moons ago, it seemed about time I wrote a little more on this subject. Fossil archosaurs of course can be represented by complete articulated skeletons down to just parts of single bones or isolated teeth. As I have discussed before, obviously not of these are equally valuable, or equally valueless, but it might seem obvious that small bits are typically of little use.
The key point here of course is just how diagnostic that ‘fragment’ is (and a fragment here can really be ¾s or more of a large bone). You can probably tell if that distal end of a femur is from a tyrannosaur and that means you must have tyrannosaurs (or for a real example, a pubis). When this might be the only evidence of an entire clade it’s obvious that this is important.
It should therefore be of interest to realise just how diagnostic individual bones, or even parts of bones can be. Chevrons for example all look pretty much alike (or at least there is very significant overlap in morphology over very different taxa) so half of one of them really won’t tell you much, but even there at least some in hadrosaurs for example look rather different to those of theropods or sauropods and can be of some use. Ribs are understandably often of little use, but humeri or maxillae say can be identified to small clades or even species in some cases and so too can little bones like the astragalus and of course neomorphs like pteroids are great.
That mean that while yeah, sure, there are some really rubbish fossils out there that are not really worth collecting, even small bits of small bones can be really important. You may not see much in them, but someone coming through the collection might well be in a position to say “Holy Cow! That can only be left tracularsplanknick bone from a derived pseudomadeupia and they don’t appear in the fossil record for another 50 million years!”. Fragments can be really important.