bodybrain data frame:
            Animal BodyWeight BrainWeight
1    Brachiosaurus   87000.00       200.0
2              Rat       0.40         1.9
3          Opossum       4.50         6.0
4              Cow     465.00       423.0
5         GreyWolf      36.00       119.5
6             Goat      28.00       115.0
7        GuineaPig       1.10         5.0
8       Diplodocus   11700.00        50.0
9    AsianElephant    2547.00      4603.0
10          Donkey     187.00       419.0
11           Horse     521.00       655.0
12     PotarMonkey      10.00       115.0
13             Cat       4.50        25.6
14         Giraffe     529.00       680.0
15         Gorilla     207.00       406.0
16           Human      62.00      1320.0
17 AfricanElephant    6654.00      5712.0
18     Triceratops    9400.00        70.0
19    RhesusMonkey       7.00       179.0
20        Kangaroo      35.00        56.0
21         Hamster       0.15         1.5
22           Mouse       0.20         0.4
23          Rabbit       3.00        12.1
24           Sheep      56.00       175.0
25          Jaguar     100.00       157.0
26      Chimpanzee      52.00       440.0
27            Mole       0.80         3.0
28             Pig     192.00       180.0
29   HumpbackWhale   39000.00      4675.0
30       Alligator     205.00        14.0
Transformed loglog dataframe:
       logbody   logbrain
1  11.37366340  5.2983174
2  -0.91629073  0.6418539
3   1.50407740  1.7917595
4   6.14203741  6.0473722
5   3.58351894  4.7833164
6   3.33220451  4.7449321
7   0.09531018  1.6094379
8   9.36734412  3.9120230
9   7.84267147  8.4344635
10  5.23110862  6.0378709
11  6.25575004  6.4846352
12  2.30258509  4.7449321
13  1.50407740  3.2425924
14  6.27098843  6.5220928
15  5.33271879  6.0063532
16  4.12713439  7.1853870
17  8.80297346  8.6503245
18  9.14846497  4.2484952
19  1.94591015  5.1873858
20  3.55534806  4.0253517
21 -1.89711998  0.4054651
22 -1.60943791 -0.9162907
23  1.09861229  2.4932055
24  4.02535169  5.1647860
25  4.60517019  5.0562458
26  3.95124372  6.0867747
27 -0.22314355  1.0986123
28  5.25749537  5.1929569
29 10.57131693  8.4499844
30  5.32300998  2.6390573
Regression Analysis for Model1:

Call:
lm(formula = BrainWeight ~ BodyWeight, data = bodybrain)

Residuals:
    Min      1Q  Median      3Q     Max 
-1851.1  -600.7  -489.1  -190.2  4995.5 

Coefficients:
             Estimate Std. Error t value Pr(>|t|)  
(Intercept) 605.92530  285.77728   2.120    0.043 *
BodyWeight    0.01661    0.01617   1.027    0.313  
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 

Residual standard error: 1493 on 28 degrees of freedom
Multiple R-squared: 0.03631,    Adjusted R-squared: 0.001889 
F-statistic: 1.055 on 1 and 28 DF,  p-value: 0.3132 

Regression Analysis for Model2:

Call:
lm(formula = logbrain ~ logbody, data = loglog)

Residuals:
    Min      1Q  Median      3Q     Max 
-3.2795 -1.0056  0.4594  0.9523  2.7481 

Coefficients:
            Estimate Std. Error t value Pr(>|t|)    
(Intercept)   2.2682     0.4676   4.850 4.17e-05 ***
logbody       0.5256     0.0850   6.184 1.12e-06 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 

Residual standard error: 1.619 on 28 degrees of freedom
Multiple R-squared: 0.5773,     Adjusted R-squared: 0.5622 
F-statistic: 38.24 on 1 and 28 DF,  p-value: 1.119e-06