Hello Bryan, funnily enough I was expecting to find any related questions to short eared owls in the bird section but found your questions here where consequently any further postings will hide your own. But strangely enough I did take a look on this occasion; hmm it must be fate, lol.
It certainly does look like a frogs skin and the second row does look like bones from its vertebrate, not sure about the others.
But as matter of interest did you ever buy (Guide to British owls and owl pellets) I recommended some time ago. Anyhow I thought it well worth another mention for any other member who may be interested in owl pellets and general information on the subject.
www.amazon.co.uk/d/Books/Guide-British-Owls-Owl-Pellets/1851532358 The guide also includes skulls and bones from shrews, mice, voles; although it is not all that comprehensive as far as skulls and bones go it may be still of interest to you and any other members.
Produced by the Field Studies Council, this chart is both an identification guide to British owls and a practical resource for investigating owl pellets. Included are colour paintings of the 5 species of owl permanently resident in the British Isles, shown both perched and at rest, illustrations and written descriptions of the different pellets produced by each species of owl and by other birds (kestrel, sparrow hawk, gull and corvids) that could be confused, and a systematic identification key to the contents of owl pellets, including complete skulls, jaws, teeth and other recognizable bones and animal parts. Text on the reverse side provides background information on the taxonomy of owls, their adaptations for hunting, food chains and conservation status. Further identification information for each species - body length, wingspan, call, and habitat, UK breeding range, main prey and conservation status - is given in a table. Guidance is also included on where pellets can be found and how they can be prepared and dissected. The chart is laminated to make it shower-proof and robust for use outdoors. This is the ideal guide to identify British owls, including a resource for information on the small mammal remains within owl pellets and the guides laminated surface can be cleaned by wiping with a damp cloth.
The following links may also help you, although I realise you are looking at frogs at the moment. I find this site particularly helpful especially when searching for a particular skull has it gives three views plus measurements.
Bird Skull collection
Finally these last two sites may be of some use
Frog Bones) this site shows images / photographs
www.google.co.uk/search?q=frog+bones&rlz=1C2ASUT_enGB387&site=webhp&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwj_kcLozPbSAhVDJcAKHdm9DQkQsAQIJg&biw=1362&bih=618&dpr=1
Skeleton of a frog
PS
I copied these very useful named parts for you just in case it was missed right at the bottom of the page.
Maxillary: bony part of the jaw.
Orbital cavity: skull cavity that contains the eye.
Quadratojugal: cheek bone.
Prootic: bones forming the auditory region.
Phalange: each of the small bones forming the fingers.
Occipital lateral: occipital lateral bone.
Carpus: each of the bones forming the wrist.
Metacarpus: each of the bones forming the part of the hand between the fingers and the wrist.
Urostyle: adaptation of one or several vertebrae, stretching the hindquarters.
Ilium: projecting hip bone.
Ischium: one of three bones forming the ilium.
Calcaneum: projecting heel bone.
Talus: bone jointed with the leg bones.
Phalanges: each of the bones forming the toes.
Metatarsus: each of the bones forming the part of the foot between the toes and the heel.
Tarsus: each of the bones forming the heel.
Femur: thigh bone.
Tibiofibula: leg bone.
Sacral vertebra: vertebra of the sacrum.
Vertebra: each of the bones forming the spinal column.
Humerus: arm bone.
Radio-ulna: forearm bone.
Scapular: shoulder bone.
Pterygoid: one of the bones of the palate, forming the root of the mouth.
Skull: bony case of the brain.
PPS
I also posted this in both threads / sections just in case, one cannot be too careful lol all the very best.
Alan
