Question: How is Girlfriends and On Our Backs related?

Context paragraphs:
Sand tiger shark: The sand tiger shark ("Carcharias taurus"), grey nurse shark, spotted ragged-tooth shark, or blue-nurse sand tiger is a species of shark that inhabits subtropical and temperate waters worldwide.  It inhabits the continental shelf, from sandy shorelines (hence the name sand tiger shark) and submerged reefs to a depth of around 191 m .  They dwell in the waters of Japan, Australia, South Africa, the Mediterranean and the east coasts of North and South America.  Despite its name, it is not related to the tiger shark "Galeocerdo cuvier"; however, it is a cousin of the great white shark "Carcharodon carcharias".  Despite its fearsome appearance and strong swimming ability, it is a relatively placid and slow-moving shark with no confirmed human fatalities.  This species has a sharp, pointy head, and a bulky body.  The sand tiger's length can reach 3.2 m .  They are grey with reddish-brown spots on their backs.  Shivers (groups) have been observed to hunt large schools of fish.  Their diet consists of bony fish, crustaceans, squid, skates and other sharks.  Unlike other sharks, the sand tiger can gulp air from the surface, allowing it to be suspended in the water column with minimal effort.  During pregnancy, the most developed embryo will feed on its siblings, a reproductive strategy known as intrauterine cannibalism i.e. "embryophagy" or, more colorfully, adelphophagy — literally "eating one's brother".  The sand tiger is categorized as vulnerable on the International Union for Conservation of Nature Red List.  It is the most widely kept large shark in public aquariums owing to its tolerance for captivity.

Cryptobatrachus: Cryptobatrachus is a genus of frogs under family Hemiphractidae.  They are found in Colombia and Venezuela.  They are commonly called backpack frogs, as the females have the habit of carrying their clutch on their backs until the young hatch; this behaviour also occurs in the related hemiphractid genera "Hemiphractus" and "Stefania".

Hemimacronyx: Hemimacronyx is a proposed genus of birds in the pipit and wagtail family Motacillidae.  It contains two species that are usually treated as belonging to two larger genera, "Macronyx" (in the case of Sharpe's longclaw) and "Anthus" (in the case of yellow-breasted pipit).  The plumage of the two species is more similar to that of the longclaws and the golden pipit, having brown barred backs and bright yellow breasts and throats.  They are presumed to be closely related to these two groups, but the split has not been widely recognised.  Both species are found in open areas of Africa.  They are both threatened with extinction due to human activities, principally habitat loss.

Paramacellodidae: Paramacellodidae is an extinct family of scincomorph lizards that first appeared in the Middle Jurassic around 170 million years ago (Ma) and became extinct in the Early Cretaceous about 100 Ma.  It was one of the earliest groups of lizards to have undergone an evolutionary radiation, with members found across the supercontinent Laurasia.  The phylogenetic relationships and constituent species of Paramacellodidae are uncertain.  Many studies regard it to be closely related to Scincoidea, a large group that includes skinks and their closest extinct relatives, and possibly also to Cordyoidea, a group that includes spinytail lizards and relatives.  Like modern skinks, paramacelloidids had rectangular bony plates called osteoderms covering most of their bodies, including their backs, undersides, and tails.  They also had short and robust limbs.

Scarites: Scarites is a genus of ground beetle native to the Palearctic, the Near East, North America and North Africa.  These beetles share physical characteristics of the more tropical stag beetles, but are not closely related.  "Scarites" can often be found under loose rocks and boards.  If touched, they often "play dead" by folding in their legs and arching their backs.  The adult beetles are predators and have been observed overpowering mealworms much larger than themselves.

On Our Backs: On Our Backs was the first women-run erotica magazine and the first magazine to feature lesbian erotica for a lesbian audience in the United States.  ("On Our Backs" is also a book written by Rosita Sweetman, which looks at sexual attitudes in 1980s Ireland.)

Myrtle's silverspot: Myrtle's silverspot ("Speyeria zerene myrtleae") is a medium-sized butterfly in the brush foot family (Nymphalidae), an endangered subspecies of the zerene fritillary.  It is endemic to California, where it is known from only about four locations just north of the San Francisco Bay Area, including two at Point Reyes National Seashore.  Its wingspan is approximately 2.2 in .  The upper surfaces of the wings are golden brown with numerous black spots and lines.  The undersides are brown, orange and tan with black lines and silver and black spots.  Larvae are dark colored with many sharp branching spines on their backs.  Myrtle's silverspot is larger and paler than the closely related Behrens' silverspot ("Speyeria zerene behrensii"), which is now limited to the vicinity of Point Arena in Mendocino County.

Girlfriends (magazine): Girlfriends was a women's magazine that provided critical coverage of culture, entertainment and world events from a lesbian perspective.  It was founded by Jacob Anderson-Minshall, Diane Anderson-Minshall and Heather Findlay.  It also offered relationship, health and travel advice.  Published monthly from San Francisco since 1993, it was distributed nationwide by Disticor.  It had the same publisher as lesbian erotica magazine "On Our Backs", but distanced itself from its pornographic counterpart by refusing to carry sexual ads.  "Girlfriends" magazine ceased publication in 2006.

Todd McNair: Todd Darren McNair (born August 16, 1965) is a former professional football player and coach.  McNair previously worked for six years as the running backs coach for the USC Trojans football team, until the NCAA issued a one-year show-cause penalty against him as part of sanctions related to the ineligibility of one of his former players, Reggie Bush.  McNair currently has a lawsuit pending against the NCAA for libel, slander, breach of contract and four other alleged offenses.  On January 20, 2013, it was reported that McNair would be hired by the Arizona Cardinals as the running backs coach.  However, on February 1, 2013, McNair said that he would not be joining the team.

Skinny pig: The Skinny Pig is an almost hairless breed of Guinea pig.  Skinny pigs typically have hair on their muzzles, feet, and legs, but are hairless over the remainder of their bodies.  Some of them have a thin covering of fuzzy hair on their backs as well.  A healthy Skinny has skin that is mostly smooth with some wrinkling around the legs and neck, the body is full with no appearance of spine or ribs.  Skinnies can come in a variety of colours and patterns, such as Dutch, Tortoiseshell, Himalayan and many others.  "Skinny" is the term used for hairless guinea pigs to describe the illusion of their visually thinner appearance, or coloquially referring to the exposed skin of the animal.  The modern Skinny Pig breed originated with a cross between haired guinea pigs and a hairless lab strain.  The hairless strain that it is most likely related to was a spontaneous genetic mutation that was first identified at Montreal's Institute Armand Frappier in 1978, in a colony of Hartley lab guinea pigs.  In 1982 they were sent to Charles River Laboratories to be bred for laboratory use and are commonly used in dermatology studies today.  They are an outbred strain that has an intact thymus and normal immune system.

Supporting paragraphs: Girlfriends (magazine) On Our Backs
Answer: magazine