Yes, those are real prehistoric bones, and yes, that is a real skull of a saber-toothed cat, Smilodon fatalis.
I took this photo at the La Brea Tar Pits in Los Angeles, California. They have a block of resin with these bones embedded in it to show the average density of bones in the asphalt of the tar pits. FYI, there is no tar in the tar pits, it’s all asphalt.
The resin block is in a glass case. To prevent reflecting yourself in a photo, put the end of your lens directly on the glass. And play around with angles and background light sources to get different lighting effects in the resin. The light coming through windows and glass doors changes throughout the day, so keep checking for interesting lighting.
You are not allowed to use tripods anywhere in the building, so bring a string tripod or monopod. Because of the lighting, you will need to use a high ISO or slow shutter speed. And be sure to check out the atrium. It’s small, but packed with many things to photograph.
I processed this image with ON1 Photo Raw. Check it out at https://on1.sjv.io/15Mjdz